Properly holding your racquet is a fundamental skill in the sport of tennis. To help teach your students, or to better learn yourself, we recommend OnCourt OffCourt Start Rite Tennis Grip Trainers (Set of 12). Having a solid object guide your fingers can be a major help when learning various handholds. This guidance system attaches on top of standard tennis overgrips, and is easily removable.
Common uses include:
Learning the continental grip
Streamlining the teaching process through a physical guide
Properly spacing your index and middle fingers
Gripping the racquet handle properly without choking-up
Helping to adjust your forehand grip from full-western to semi-western