One of my favourite simple training aids is a lone coin placed in the cavity of a putter or on top of a mallet styled putter head.
The idea is to swing your putter without allowing the coin to fall off the club head. Putting is all about rhythm, and you’ll need rhythm to keep your coin on board. Any flinch or hit in your stroke at all will result in the coin tumbling to the ground.
Give it a try next time you practice your putting. It will smooth out your stroke beautifully.
/ Kevin Haime, 2000 PGA of Canada National Teacher of The Year