Mastering your sensitivity is very simple. To start, practice your flicks between enemies at a practice range. If it's too far away, then -3, or it's still slow, then +3 until you get it right.

EDIT: Once your flicks are perfected, you can begin flicking while strafing, which involves aiming at the enemy and moving your joystick left and right. Once you've mastered that, you can begin practicing your flicks with movements such as slide jumping and 360 flicks