be confident
if you make a call your team has to be 100% commited to it, even if someone thinks its a bad call its better to do it than have half of your team doing something different
you will make a lot o bad calls but like anything thats how you get better at it
you dont actually need to watch a maincaller stream, a good team its enough since you can hear the entire mumble
anyone from invite should be good
press tab a lot

sigma wrote a guide to this a while ago:
http://teamfortress.tv/articles/view/33-momentum-in-tf2-a-push-guide

Keep track of:

# of players up on each team
Health of your team
Relative position vs. enemy
ubers (I found a stopwatch app that I overlayed over my tf2 window that I used to keep track of ubers, made things really easy)

If you are at a disadvantage in most of those categories, you should hold passively or back out completely. If you are at an advantage, you should be looking to get more aggressive and bully them out/uber in and kill them. After some practice you'll get used to judging a situation and knowing where to direct your team. And as you get to know your teammates better, and the enemy too, you'll learn when you can get away with taking riskier moves and whatnot.

For the most part, you can just keep track of those things and know which team has the advantage. Use that to decide where to hold, and when to push in or back out.

Know the right moments to make a call.

Don't talk too much.

If you aren't sure on what to do, ask your team what they wanna do.

Know that even though you are the main caller, you still have to listen to your team, and you shouldn't have to talk over them.

As nemo said, press tab a lot, give your team info when they're busy fighting (eg. guys we're 3 v 4 right now).

If you see someone doing a lot of damage/going in but not calling it, try to help them out and call their damage if you can, or ask your nearby teammates to assist; however, if you see people doing this stuff like not calling damage etc...talk to them about it after the game.

I think it's hard being main caller and playing medic; I feel it should be the pocket who does it, but every team is different.

Those are just some things from the top of my head, and they probably aren't very helpful, sorry.

good luck

^ What vanilla said.

The basics:
Uber (also watch for kritz)
Their classes up (note pick classes or heavies, snipers classes can be pushed into aggressively if you can keep them pinned down while heavies must be carefully focused during a push)
Heals/Damage (is your team buffed? is theirs lit? sometimes you can push off that)
Positioning (are they backed away from the choke? if so you can usually bully in)

Some "tips":
Know your team's abilities versus theirs. You have better scouts? Take uber fights 1v1 so your scouts can win the post uber. You have a better demo and pocket? Bully in a bit and try to force uber.
Favor aggression if you have mid and defense if you don't. You don't want to push with a tiny advantage into a team defending middle, while it is a safer bet to push into 2nd or last with a small advantage as you have less to lose.

#1 rule of calling. Calling is less about making the best tactical decision and more about making sure your team is all on the same page.

I personally don't understand how anyone could play Medic without main calling. I'd be so bored.

As a main caller, "splitting" the main calling is a good thing, well according to me. What I mean by that is that having your Pocket call too would be great, because he has a better view of the fight and that kind of stuff. As most people said, keep track of any kind of advantages/disadvantages (Player advantage, uber advantage, postioning advantage, etc.), and calling focuses is an important thing to do (better to have your Pocket do it imo). Also, calling when you pop the ubercharge can be important for your scouts, and also you need to call what kind of uber you're going to do (solo Pocket, demo + Pocket, double scout, etc.), and where you guys are going. On mid, always press tab and call ASAP to back up if your team is down numbers (except if you lost 2 scouts and they lost a demo, for exemple). If you do all that stuff, you're an awesome main caller.

The best thing you can do is enjoy it - find a way to enjoy main calling if it doesn't come naturally to you.

If you don't enjoy it then it won't be a good long term solution as you'll get tired of it pretty quickly.

All the other stuff will come with time, practice and patience.

It's on the same page as being confident, but you have to kind of demand attention. Your calls should emphasize that it's important. If you have monotone calls your team might miss it. After all, they're focusing on other things as well. Also, it's a lot more effective if you use names rather than classes when you make calls. For example "Vortex cap, everyone else go second" is more effective than "Have one scout cap, everyone else go second" because there's no confusion and simply saying someones name or alias makes them perk up and pay attention.

As a side note, it's not exclusive to main calling but try to stay positive. Don't try to pull everyone into a dark mood after a bad midfight, and don't fucking drone on about everything that went wrong. Quickly acknowledge the problem "if our demo dies at mid immediately we should back out sooner" rather than pointing fingers or droning on and talking about it during the next rollout and midfight.

At Medic I personally like to keep a flow of information going, not only to keep my guys informed but also to keep my mind in the game. By getting my team to talk I can keep "tucked in" to a corner near my pocket/demo and expose myself to see what's going on.

Generally I call when spawns will come in for us (Combo up in 5, Demo up in 10, etc.), track uber advantage (and call if I suspect they're on Kritz), and buffs (we've got buffs, flank is playing outside their health range).

The key to calling is to have everyone follow your calls and trust you.

Sometimes you will make a bad call, but sometimes a bad call can still work out if your whole team executes it perfectly. Your bad call will 100% of the time be a terrible call if 3 of your team mates follow the call, and 3 of them decide that they know better and don't go with the play.

The other thing to remember, is sometimes the call could be perfect, but some enemy hero scout comes in and cleans up all 6 of your team. Once a call has been made, and the actions executed, regardless of the outcome, focus on what is going to happen next, don't just simply bitch about what went wrong... focus on the task in hand.

Oh and also, be decisive. Take into account any input your team mates have on the situation, but when you decide to make a play, you tell your team, and you make that play. Don't make questionable calls such as, "Hmmm I think we should push now?". Just say, "Go in now, push!". Repeat it if needed. You can also collect your team after a push went wrong...

"Okay that was a bad call guys, sorry for that, but here's the situation we are in now so let's focus and work as a single unit".

Main calling should fall on the pocket's shoulders, after all he can see around that corner and you can't. Besides, it's much easier for a pocket to main call than for a medic to do it.

Medics have way too much other shit to worry about. Meds should just be focusing on tracking enemy ubercharges and calling out enemy positions/threats.

Just tell your pocket to sack up.

You could also argue it might be easier for a medic to main call because they don't have to focus on DMing and can look around freely. Anyway, the pocket sees things the medic doesn't see, and the med sees things the pocket doesn't see, such as overall positioning and health. It doesn't matter who is main calling as long as all those things are being communicated. Main calling doesn't mean you're the only person on the team who should be talking, or even the only person who can make calls.

If you are afraid of making a bad call and hesitate as a result then you've probably already lost. Be decisive, but at the same time don't be afraid to cancel a call if the situation changes (eg you're pushing and you suddenly lose two players). Just try not to "un-cancel" calls too often though, because nothing is worse than telling your team "Get in! No wait get out! Actually get back in!". It is very likely that the confusion and chaos created by rapidly making contradicting calls will cause your team to lose regardless of other considerations.

Whenever possible, try and tell your team ahead of time what they're going to be doing. It is much easier for your team to coordinate and prepare if they have at least a few seconds warning. The most common example is calling that you're going to push when you get uber. As long as you call your percentages your team will know exactly when to start moving.

Your team may lack context for some of your calls. It is good to be specific as possible within practical limits. If there is information that would be useful to your team and it can be communicated quickly and efficiently, then you should incorporate it into your call. Just calling "push left" often doesn't give your team very much to work with. You should tell your team who is getting the uber and approximately when you're going to pop it. For example, "I'm gonna take pocket and scout left side. We're popping through". If you're holding your team needs to know whether to hold close or passive. If you're pushing it may be useful to tell your team to push slowly or to "go aggro".

It is good to give your team "status updates". Basically, since you are probably the best judge of what the overall situation is like it is important to communicate with your team how the fight is going and what their priorities should be. The most important example of this is to tell your team how effective your uber is ("good uber" or "bad uber" is simple and to the point). If your team hears "bad uber" they know to gtfo. Other common examples include "Our health is shit. Back out.", "We're winning this, keep pushing" or "We have to deal with the stuff behind".

When something needs to be done calling a player by name and telling them to do it usually results in it getting done faster and with minimal confusion. If you just say "Someone go sac for their med" the results are unpredictable. Mostly likely there will be a huge delay before someone does it, but it is also possible that no one will go or that two players will go and die instead of one.

As maincaller it is important to be able to predict the actions of the enemy team. Being able to anticipate how, where and when they will push, whether or not they will run kritz, what offclasses they will use (if any) and most importantly, how they will play at mid will give your team a significant advantage. It is good to predict how the enemy team will act both based of what you would do in their place and how they have played the game so far.

It is good to learn (or even develop if you're feeling bold) and have your team practice "set plays". I struggle a bit to define "set plays", but I suppose the simplest definition is a push where there is a very specific objective in mind and/or some players are given very specific roles. Some examples I can think of off the top of my head are the "heavy push", the "4 man sac" and the "wraparound". Being able to properly execute these plays will give your team a huge advantage. Since these plays are usually super effective against teams that are unprepared for them it is a good idea to teach your team how to counter them as well.

The language you use should be as consistent as possible when you're calling. Using the same words and phrases every time you make a call helps your team learn and once they get use to the way you call they should react with greater speed and confidence when you make a call. Its nice, because after a while you can use fewer words (or even maybe just use one word) and your team will understand your meaning exactly.

That is all I have for now. I can't actually believe I wrote all this crap. Sorry in advance if it is an incomprehensible mess.

I disagree.

Pocket callers and medic callers are both viable and both have different advantages/disadvantages.

While the pocket is a much better judge of the health and positioning of the enemy team, the medic is a much better judge of the health and positioning of his own team.

Just as a medic might miss a fleeting opportunity for aggression, a pocket might push forward without realizing his team has very low health.

Either pocket or med can maincall, but ideally they should share the responsibility at least a little bit. Because, if a medic is main caller, but he trusts his pocket enough to make some calls also then it should be the best of both worlds. Not everything is black and white.

I main called as med during my first season of open. The most glaring draw back to a medic main calling is that in most situations you won't see what your pocket/demo sees. Make sure your pocket calls out anything in front of him. He should be your second pair of eyes. As long as everyone else has clean and concise coms everything should naturally fall into place.

So true.

Everyone needs to give helpful information. Don't think you're hogging the coms when something important needs to be said. Helpful coms helps everyone around you, esp the "main" caller.

My two cents.

I've been main-calling for about 3 or so years now, and I've gone through many phases. I'll drop a few points (they've probably already been mentioned).

*Have a firm, authoritative voice. People may sometimes not hear your calls/shrug them off if you aren't firm with them. It's all about using tone and the right words. Compare your self saying "Scout behind" and "SCOUT ON OUR MEDIC". Don't be afraid to tell people to stop talking if they're cluttering comms with "Haha lol xD lmao i rayept dat guy!"

*Be confident in your calls. Even if it may not be the "100% super strat 360 69" call, if you make it seem it is your team will follow it to the letter. Relates to my above point.

*Don't think you need to micromanage. Your team needs to know what they need to do, and that doesn't require you to play Starcraft in TF2. There may be some situations where you need to say "scout come in now", for example, but I tell so many people this particular quote regarding this. "When I give a minister an order, I leave it to him to find the means to carry it out."

*Don't be afraid to ask for information. As the main caller, you need information to make calls. "Knowledge is power" as they say, and that makes calling no different. A fight may be difficult/dire on your end, but for all you know someone on your team could be flanking them, potentially turning the tide of the fight.

*Short and concise. For christ's sake, we're not doing speeches here. Make it short and sweet, don't drone on as it can tend to clog comms and will end up having a more negative than positive effect. Not only that, please be clear in your meaning. Your left could be someones right.

*Try narrate the uber(s) to the best of your ability. Post uber is probably the most important phase of fights in TF2, and is often where a lot of rounds can be decided. Saying things like "their uber is almost out, they're stuck in trash" can work wonders for your team, setting up massive flanks and the like.

*STAY POSITIVE. This is probably the most important part of calling, and where many people fumble, no matter how good they are (I am sometimes guilty). If you start getting frustrated/upset at what is happening, be it your performance or your teams, please get a stressball or just scream at your monitor without holding down your ptt button. When the leader/caller starts getting low on morale, everyone else in the team will quite often follow suit.

*Relax. Quite often you will find yourself pretty taxed after a game. If you've played a few games and are tired, go get a drink of water and take a couple minutes break. I daresay more often than not most teams are willing to wait a couple of minutes for a "bio break", so just use that time to reflect on the game, your calls, and how you can improve for the next map.

Hope this is helpful

Can we get a ban please?

It's a link to a rar file. Ban and nuke all posts, he's posting that link in a ton of threads.

Something I'm getting back into after switching back from demo to soldier is picking up the maincalling as well. The ultimate thing you have to remember is that everyone is listening to everything you are saying and are making their own decisions and playing off of that. So whether or not your pocket just destroyed that scout, if you want him off of you as medic you can just call that the scout is destroyed so that your team focuses him with their greed for a frag. Stuff like this is pure manipulation of your teammates but if you explain to them that you are guiding your comms to deny the biggest threat or push the largest advantage, they will listen. Don't make selfish comms just to make yourself look good, think of the big picture and constantly be talking and calling YOUR position. No one gives a shit what the other team is doing unless it's wipe-threatening (kritz, heavy, etc). Call what YOU are doing and where you want your team to go and you'll have a much better time than reacting and calling what the other team is doing.

Example of a bad main call:
"Their roamer is sewers, he's going to jump me, help he jumped me, shit I'm dead."

Example of a good main call:
"Their roamer is pushing sewer, everybody move IT their demo has choke stickied. Watch for the roamer to overextend, then we push. Roamer's in, dead, let's go."

Same situation, only because you said what you wanted your team to do, instead of a vague bitchy tone that sounds selfish, ie you just don't want to die; you set up your team for a confident play before, during, and after the event you were scared of dying from.

Good luck and remember your attitude translates to the rest of your team! Stay positive!