...And found this: https://www.reddit.com/r/truetf2/comments/3onleo/a_guide_for_somewhat_high_level_scout_play/
Before I start, I'd like to say this is coming from someone who has never played scout in a competitive league before. I'm only giving DM tips. I've played in UGC since s13 though, so I'm not competitive phony.
I used to get shit on by steel level scouts, but with some basic things that I practiced, I managed to be able to out dm most gold level scouts. Here's what I changed.
First off, you need a good monitor/computer. I used to play on a shitty mac laptop that gave me 30-60fps and I was able to play in steel as engineer, the class you don't need to have good aim to play. I was so bad with this potato, but once I got a new computer with a 144hz monitor, it felt like I was playing quake in slow motion. Scouts who were once fast were now walking the speed of a demoman. The difference is outstanding and if you ever care about getting into high level play, you need a better monitor if you have a standard 60hz low res monitor.
Second, I lowered my sensitivity and turned off mouse acceleration. I realize this isn't for everyone, since b4nny is known to be the best if not one of the best players in TF2, and he plays with a high sens to get those double strafes in. Personally however, I could feel my shots being more accurate, and I could actually aim rather than predicting and guessing where my shot would go. This skill is necessary if you want to have competent pistol and scattergun aim.
Third, my movement changed in several ways. I stopped double jumping every time for no reason, I started strafing with every jump, I made my movement less predictable by jumping on props landing off, faking a jump onto props just go to the left of it etc. Another huge thing is I started playing passively. I see so many scouts playing aggressively and it's so fucking predictable, it's not funny. When I used to play aggressive, I'd just keep jumping on props until I was on the enemies head. It wasn't until I got into silver level soldier that I realized how predictable this type of movement was, because you could just get a feel for exactly the scout was going to do next if you played 100 hrs of MGE. The last thing I want to say about movement is that you need to read the enemy, and fake them out. Say you're on gullywash and you just destroyed their scout for 100, and now he's going bigdoor. You go from point to bigdoor expecting him to be going right for the healthpack, but a completely mind-fuck would be the scout taking bigdoor wide and coming back to fight you head-on. It's so easy for that scout to just meatshot the other scout twice before he can react, and there's plenty of situations like these where you just have to read the enemy and make these types of plays. This stuff starts getting old in invite, but I can't really give tips for that level.
Another thing I want to go over is aim. I watched this video of clockwork showing how to aim with strafing, and I believe you're just gimping your skill with that. Like I guess if it works for you do it, but you're not getting better with your aim. If all you do is aim by strafing, the enemy will counter that by having movement that you just can't have competent aim against with strafe aim. You have to practice aiming with your mouse, and this goes back to having a good monitor, since you're able to see the enemy so easily. It also makes it easier to hit scouts who like to have an aerial advantage instead of waiting for them to land and hoping they can't read your aim.
I hope I helped someone somewhere, and if there's anything wrong or more I should add please point it out to me.