Quick one for you, I, like many people, used to get a really painful racquet hand through gripping tightly for the length of the game, so.....

Top Tip:

Buy an extra grip and wind it around the old grip, so you have one on top of the other. This increases the circumference of the grip, which means you are exerting your muscles and tendons through less distance, which means you use less energy.... its easier on your hand

Worked for me, although it might only work with people with big hands...