Warm up?

Try warming up on a DM server before your game. Don't go for big plays at the start as well just play with your team call your bombs and do what you can.

Do you warmup? Play some dm or mge servers before you play scrims.

warp

=

Watch your own demos with someone and go over what you did wrong then reflect on it

It seems like your problem is you need to feel out the team before you can go bananas on them. Play more passive in the first few rounds to try and feel out the enemy team than continue on as usual.

I usually take a map to warm up properly regardless of how much dm, mge or jump maps I play. Maybe it's subjective but for me it always takes at least a few rounds to start comming effectively, listening to comms and just generally pay attention to what's happening in the game.

have you considered the possibility that you are just an unskilled gamer?

in all seriousness I agree with the people saying you should play more conservatively at first, at least until you figure out what you can get away with doing
for example if you play against a team that likes to play mid super passively, you want to be aware of this so you don't jump in and feed their scouts every time
as roamer a lot of your plays will depend on how good the enemy team is at hitting their shots and/or weather or not they decide to focus on cleaning you up if you jump behind, so if you're not familiar to how the enemy team plays you may try to distract by doing a high bomb or going behind on middle, just to see that your entire team is dead because nobody paid attention to/shot at you

=

Picking something specific before the match and focusing on improving it during really helps nail down performance in my experience.

https://www.youtube.com/watch?v=SmsRN78qMxM

Might just be a mental thing. Takes some people a while to get completely focused and to remove external thoughts/concerns. For example, at the start you might worry about how you are going to play/not losing/etc, but then after 10 minutes you just focus on the game moment-to-moment so perform better. Dunno.

=

play with the mindset of remaining calm throughout the entire game.

never go in with the mindset of "I'm going to wreck their entire team." It will NEVER happen.

Why would it never happen?

well you can either try to play reeeeally passive on the flank first, not let flankers etc and learn their habits or play reeeeealy aggressive first and learn their weaknesses, you won't have as bad a game once you know all that

I'm an absolute fucking wreck the first 2-3 maps whenever I play. Once I'm that far, I just want to play all day (and that's usually when people stop).

I'd say 6v6 warm ups, but if it's the practice you're messing up, I'd probably just suggest longer sessions for practice really. Flicking around on MGE won't really recreate the easing-in of just getting comfortable with 6v6 again the same way.

assuming you are one of those guys who starts sweating pregame and complains about cold fingers, go into the game with the mindset that you are gonna roll 5:0 and dont worry too much about doing badly.
edit: this especially applies to roamer, where your overall performance can vary a lot depending on map and enemy team.

Well if you believe it won't happen it won't..... you just got to believe...

Soo, take this with a grain of salt because I play medic, but I definitely also feel like I have to warm up my decision making. I think it's partially because my job and my schoolwork are both mentally taxing. I like to do the following activities before scrims:
- play pugs
- watch my own stream vods from scrims
- watch my pocket's stream vods
- watch povs of better players, and not just my own class
- talk strats with teammates
I find that no single one works for me as a warm up for too many days in a row, so I rotate those things.

its prob nerves fam
you prob do good later because you get used to it or somethin