I had a tendency to get open in the shoulders which would lead to me pulling putts. I tried cross-handed for a while and that squared them up nicely, but it never felt comfortable.
My coach suggested the grip that you see here. It’s one that he had used for some time and I find it much more comfortable than the cross-handed version.
The club is held normally by the left hand, but you then place your right hand over the left, so that only your thumb and index finger are touching the rubber. Apart from giving you a nice square stance, this grip also means that you can’t grip the club too tightly. It actually feels a little insecure at first, but one you get used to the feeling, I find that it works really well.
Arrange your fingers over each other in a light way that feels comfortable.
Side by side
Sit your thumbs next to each other to help your shoulders square thoughout the stroke.