A consistent putt is the best way to improve this aspect of golfing. Training muscle memory helps your body to recognize and settle into the correct alignment ahead of the putt and to follow through correctly as you putt so the ball travels exactly the distance and direction you want it to go. The best way to develop muscle memory is repetition augmented by visualization exercises (helped by putting mirrors and marked mats) and slow-motion training (helped by wrist alignment cuffs).