Make sure to go in options and turn all the special settings for your mouse off except for Raw Input. Mouse Acceleration is very bad for muscle memory and coordination because how far you turn will depend on how fast you move your mouse. This is bad, as you can move your mouse one inch slowly and turn a small amount, move your mouse one inch really fast and youll get much farther. You want to have an even and consistent ratio with the distance you move your mouse and the distance that your crosshair performs in game for your brain to register a consistent movement.
To get better at accuracy and aiming, you have to find your sweet spot for sensitivity. Most if not all good players i know use low sensitivity, anywhere from 0.3 to 1.25 (it also depends on your mouse DPI). To estimate if your mouse sensitivity is too fast or too slow, choose a static spot on a wall, turn your mouse a good bit away from it, then try to flick one shot that exact spot. If you go too far every time, your sens is too fast. If you go short every time, it's not fast enough. If you're using a high sensitivty (2.0 and up), lower it in increments instead of instantly trying 1.0 (which you will automatically find to be too slow and be frustrated about).
Patience and practice is key. Also, frustration blurs concentration, remember that. It's much better to not care than to rage.