photo credit: Pierre -M- Most amateurs do not align themselves properly. Let's start with the ball position. The ball should be one ball width left of center in your stance. When looking down at the ball your left eye (right handed players) should be one inch on the inside and one inch behind your ball (drop a ball while in the address position to test this).
Keep your shoulders level to prevent your right should from coming over the top during the forward swing. Make sure your feet, knees, hips and shoulders are perfectly square to the target. Stay completely motionless when striking the ball and make sure your grip is correct Practice these tips and putt for doe, not for show !