There is a slight difference in the way that you grasp your putter compared to how you grasp your irons.

Let your arms dangle note how the hands naturally hang now put them on the putter like this. After you have done this, move both your right and left thumb straight down on the grip of the putter.

The reason for holding the putter like this is to restrict any excessive hand movement, and also to prohibit you from turning your hands over in any more be it opening or closing the putter face through the impact.

Jordy Scerbo