The Meter Stick
Get a metal meter stick and place it six feet away from the hole (or any target) on the line where the ball should start off the putter face. Set the ball on the end and hit your putt. If the ball stays on the meter stick the whole way, it means your putter face was square at impact and you put a good roll on the ball. This is also a great putting drill that you can do at home.
Spend an hour with your putter today