This drill is really important as it gives the feeling of a correct putting motion and helps develop feeling for the correct impact position. Start by setting up a putt two or three feet away from the hole. The reason for this distance is that a putt of this length doesn't need much backswing movement, instead allowing you to 'feel' the putter head's motion. If you are right handed, adopt your usual grip and then take your left hand away. Your putter and the ball should be in their normal positions and your right palm should be equal to the direction of your putter face. 

As you make your putting motion your right wrist should remain at the same angle and not break. Repetition of this one-handed drill should help you sense the correct technique to use on the course.