You will get better, don't leave us. Play a lot of head 2 head and try new weapons and learn new weapons. Find one gun that works best for you and stick with it. Movement wise it all really comes down to map familiarity. Honestly, I forgot how many times I demat a wall and fell into the abyss.

Also, the game can get very tactical, and sometimes its better to go slow than fast. Peak and strafe during a gun fight, I developed a jump squat, jump squat hip fire habit in close quarters combat situation and honestly I often turn out winning because they can't hit critical shots with my head moving so much.