Keep your racquet away from heat. This means don't store your racquet in the car trunk during summer. When flying during summer months, carry your racquets on board instead of checking them with other luggage. Also, be sure to rotate your racquets regularly for even wear and tear of frame and strings. Replace your grip.
Many players overlook the importance of their racquet's grip.
If your grip is worn, there is a much greater chance of the racquet twisting in your hand which can contribute to arm problems. Have your grip checked each time you have your racquet restrung.