A tennis ball machine can provide very good practice. They don’t care where you hit the ball, so if you’re a beginner missing half your shots, you need not worry about failing to give your partner a good game. The predictability of a tennis ball machine is both an advantage and a potential disadvantage. If you need to groove a stroke, the repetition of a consistent feed is just the ticket, but you have to be careful to avoid the lazy footwork that can easily result from knowing where the ball will be. Ball machines range from inexpensive, tiny, battery-powered units that pop out a short, soft feed to near bugs that can generate almost any speed, spin, and placement pattern you could want. To read more about tennis ball machines go to Tennis Ball Machine Central.