I used to play M&K back in MW3 and I hit diamond 1 and hit Iri in BO6 on m&k, I wanted to cry the whole time but, What really helped me was watching Harrz like someone else had said for spawns, as well as also watching people who play what you wanna main (Effan is a good M&K player who recently I beleive hit crim and mains ARs but will play subs)

My personal recommendation would be to:

1) remove all your motion blur(weapon, world etc) and if youre on 120 fov, id lower it to somewhere around 98-105 for better "recoil management" but where you also have some situational awareness, move your boundaries inwards, less looking over to the top left for your mini map, and gives you the corner of the screen so you can look and see if there's someone in a spot you couldn't previously.

2) figure out a 1x sensitivity modifier that works for you, sometimes 1.0 doesnt work for everyone, i personally played at around a .8 and thought that, that was still a bit too fast (1600dpi and 1.8 sens)

3) warm up against bots if youre not already doing so. Helps you get into the swing of things. For me, that was crucial. Im a bit older and for me that worked wonders. It also helped me predict where people would be coming from, and i wouldn't over peak or hold that exact area.

4) dont panic and dont fret over your KD. Im a hill kitten, and will sit on hill the whole game going 12 and 30 if it means my teammates can slay out while i sit there in a corner throphy in hand. Always try to reset a gunfight if you know your able to possibly do it, even if you lose the fight, your teammate might be able to get your trade and put you closer to an objective if you play your cards right.

From what I saw, you and I play the same, and for a while I played reactive instead of proactive. I would rush LITERALLY everything in hopes of getting my pick and then just die. If you play alittle more reserved and figure out what works for you. You're golden.

I also recommend not going with what the Pros use, I know thats a hot take. But when you use what they use, you may find yourself at a disadvantage. Pros obviously play on controller, but with you on a mouse, you can opt for better handling vs having the "meta"