Insight from Mitchell Moncrief on Backswing.com:
Very simple…make sure the last thought is speed..most amateurs leave their putts short..for that matter, they leave most shots short..picture a 2 foot circle behind the hole and get the ball in the circle. Amateurs focus on line and forget speed. Pros focus on the speed to determine the line.
It all depends on what fits your eye. I would say for sure go with a bigger grip so your hands become less active. Odyssey stroke lab is a good place to start.
Relax your grip and be on lead side at impact. Most amateurs have a lot of weight on the trail side of the body at impact. Tour players have 90 of weight on lead foot at the strike.