Warm up by doing some stretches for you thigh and calf muscles, then do some light calisthenics and jogging in place. Most clubs require players to wear eye protection. You should not depend on your regular prescription glasses, because they are not designed to give enough protection. Also, open eye guards don't protect you eyes well enough. Don't ignore cramps, pain or fatigue.
Most major injuries result when a player keeps playing after an injury.
Always allow at least 18 inches between you and your opponent during play. Don't be afraid to hold your swing or stop play if you think you might hit your opponent with the ball or the racquet. Many injuries occur when one player is more experienced that the other. If you are the more experienced player, keep your guard up and tone down your shots. If you are the less experienced one, do not expect to defeat your opponent by taking unnecessary chances.