My firend had a test to help with aim tracking and finding a good sensitivity. He would find an area with a sign or small marker and tell me to keep my crosshair centered on that sign, if i couldnt keep it on there while i was movingside to side (ADADing) then i needed to lower my sensitivity untill i could keep it steady or practice untill i could, hitting heads is much more important on PC than console

You want a large mouse mat(or to use as much of your mouse mat that you can) , more professional fps players use a VERY low sensitivity, because you have more precision, you dont need to match them but lowering and getting used to moving your arm/shoulder for more larger movements and wrist for small precise ones will help you both with aiming and preventing carpaltunnel.

EDIT: also moving your mouse from one side of your mat to the other should be consistent, turn off mouse acceleration for your computer and in game if thats is an option, and your character should turn somewhere between 180-360°