One to the skills that separates the average player from an advanced player is staying square to the ball feet when making a shot. This means your feet are parallel to the ball and not parallel to the net. You should try and position yourself perpendicular to the net and not facing the net. This positioning gives you more power and directional control on your shots. If you are spraying your shots all over try this positioning. Here is a link to a video on the subject.
