The only thing I could tell you is that being sure about yourself. Try to have a good confidence on you, it's the key of everything! According to my own experience, I saw a lot of people doing shit, especially in clutch situation where everybody is watching you, doing weird plays/moves or taking really stupid decisions while they are actually good players in general.
Aswell, communication is something really important (but I guess I'm not teaching you anything lol). So don't forget to tell what you're seeing, doing or going to do. But of course, your team must follow in this attitude.
And talking about team, it's way better to play with players who clearly speak your language or with friends than playing with some randoms guys. It will be better to coordinate your plays and just avoid some non-sense rounds where everyone is doing his own stuff separately, things which happen everytime with randoms.
Play a role that you're comfortable with and stick on it. Don't play B fix during 2 maps and A rotation for the next games. It's clearly dumb because it will confuse you 100%. Same for the T side by the way, don't play lurker if you don't understand what is going on during the round ^^
If you really want to raise your level, do not hesitate to learn flashes, smokes and molotov spots obviously.
But above all, don't forget that CSGO is a mental war and requires some knowledge and experience of the game. and it takes a long time to be honest....
Just to finish, one thing that has really helped me develop my game and my in-game state of mind is watching professional CSGO player streams (or videos on youtube) when they play FPL such as s1mple or niko for example. It's definitely a good way to learn and understand strats, peeks or economy and having fun in the same time
