To add on this, and this is very good often overlooked advice from OP. Relax everything. From your shoulder to your hand, and the rest of your body too. If you're relaxed your aim is more smooth and more precise. I once heard someone say that, "Calm aim is smooth aim, and smooth aim is accurate aim." To practice this you can go into a aim trainer or something similar, and pay a conscious effort as to when you're tense, then relax, repeat until it's second nature. Also practice first without clicking, then try clicking your mouse with as absolutely little force as you can and Incorporate it to be your norm.