I used to play for fun, so take my advice with a grain of salt, but here are things you should be doing.
- Aimlabs is not warm up. Warmup using death match or the practice range.
- NEVER train before your games, it will tire you out and make it harder to focus on the game.
- If your pc is strong enough, record your games and watch them. It will be so much easier to notice what you are doing wrong when you aren't focusing on the match. While watching imagine a perfectly played scenario and try to pinpoint what the issue could be and than search for ways to fix it on youtube, if you don't already know how you could fix it.
- Don't fill. While filling what your team needs is good for winning games, you will be too busy focusing on your util to think about the other aspects of the game. Just choose 2-3 agents you like to play the most and stick with them.
- After choosing your agents, learn those agents fully by watching others play them. Or maybe even watching guides for the specific agent, even though I don't personally like guides as they aren't subjective enough for a specific players playstyle.
Can't think of anything else at the moment but hopefully this helps you out 👍🏻