Cocking your wrists on the backswing creates a tremendous amount of power that is imparted on the ball when the wrists uncock at impact, you can do this three ways, early, late or swinging, see which works best for you
Match the movement of the club with the movement of the body to arrive back at the same point
To be a good short putter you need a simple swing with very few moving parts so that you can return the putter square to impact every time.