You want your elbow at your eye and the ball to be from 3/4 to the end of your head to the middle.

These are the best pictures for form:

Kobe:


MJ:


Redd for you left handers =P:

__________________
I'm Chinese =P
Height: 5' 9"
Weight: 145
Wingspan: 6'1.5"
Reach: 7' 6.5"
Standing Vertical: idk somewhere around 30
Running Vertical: idk somewhere around 33