Ideal grip type (material) and size allows proper release of the golf club and less tension in the player’s hands and forearms.
A light touching of fingertip to thumb-pad on top hand (glove hand, will indicate the correct size grip.
Fingertips are separated from heel
of the thumb-pad.
Fingertips lightly touch heel of thumb-pad
Fingertips dig into heel of thumb-pad.
The material of the grip is a personal preference. The grip should be comfortable and playable especially if wet from rain.