Better footwork improves your game
Everybody knows about the importance of footwork in tennis, but how do you actually improve it? Working on your fitness level is important of course, so jogging, aerobics and working out in the gym would be one option. Rope skipping is very good, because it improves both your fitness level and your coordination.
But there is a technical aspect to it. One thing you should learn is the split step. Next time you watch a tennis game on TV, do not follow the ball but watch one player all the time. You will see that whenever the opponent hits the ball, the receiving player seems to jump up a little bit. Actually, he pushes himself off the ground, lands with his feet a little wider apart and in a "ready-to-move" position. It is like a wake-up call to the muscles, making them ready for a sprint towards the next ball.
Another function of this split step is for the player to be in a balanced position facing the opponent, so that he is able to start in either direction. By properly executing the split step, you will never be caught on the wrong foot, and you will shorten your reaction time.
You have to extra work to do the split step, but the upside is you will have more time to get to the ball, thus reducing the amount of energy needed to reach that next ball.