After teaching tennis for almost 30 years, I believe the greatest change you can make in a players game are as follows:
- Gradually open the stance rather than keep the traditional closed stance.
- Convince them to gradually change the forehand grip toward a semi-western rather than an eastern or continental grip.
- Teach them the importance of a continental (universal grip) when at the net.
This is especially good for those players who have been playing a long time but never seem to get better and continue to make the same mistakes repeatedly.
The open-stance will force a player to hit with their hips and legs, not just the arm. The open-stance will stop a player from taking too much back swing and recovery is immediate.
The semi-western grip will force a player to "brush-up" on the ball. In the past most players have pushed or guided the ball. With the semi-western grip, you can teach a player to have greater racket speed immediately. In addition, the semi-western grip aids in preventing the classic tennis elbow. It forces a player to keep their elbow close to their body before extension into the ball. Once a player establishes their forehand as a weapon, you will find other parts of their game will become more proficient.
Once a player becomes comfortable with the continental grip at the net, you will see them become less confused under pressure and develop quicker hand speed. They will start hitting with more underspin, thus improving control. It will aid in forcing more wrist-snap on the overhead, which should translate to a marked improvement on their service motion.
When I see a player, I always think, "what I can do to make that player an "A" level player?" I truly believe most players can attain that level. These suggestions might help you attain your goal.
Good luck on the court!