What we see most good putters do is have one source of power in their stroke; it either comes from their arms or from their shoulders. Very few putters are putting from their wrists anymore.
The Proper Putting Grip
First, they take a grip that does not promote twisting of the clubface and then they make a stroke where there is one source of power. If it is from the shoulder, when the left shoulder goes down the putter goes back, when the left shoulder come up the putter goes forward, back, through, about an even stroke on both sides. That would be one source of power using the rocking of the shoulders to move the arms.
Arm Position for Putting
Another way to putt would be leaving the shoulders pretty still and just swinging the arms, now when I do that, the right arm might bend and straighten at the elbow. But again, one source of power, no power from the wrist. Strangely enough, the people with the long putter are doing that, they're using the right arm in a piston type fashion to push the club.
Both work very well, but the main deal is apply your power to the end of the stroke, not just to the ball. So if I rocked my shoulders, I would want to apply the force to the end and hold my finish. If I did it with my arm, the same thing would be true, my right arm would bend and straighten but my force would go to the end. So remember, apply the force to the end of the stroke and only one source of power; choose it in practice, use it when you play.