zac, the best way to see your form is to draw next to a full length mirror or have a friend watch you. If you have a tendency to tilt your head back or start a backward arch in your back your draw is too long. If you find you are head forward or stretching your neck forward to line up, you're draw is too short. A perfect draw length will have you standing erect with no head tilt. With good form you will also last longer when shooting multiple targets.
Good Hunting...