What you need:
Sit as close to courtside as you can without interfering play. Start by photographing the serve. The two most interesting parts of the serve are the toss, which show the athlete poised to strike, and the smash, where the server makes contact with the ball. Observe the server a few times to get the timing, so when you shoot, you will get what you want. The smash happens fast!
Keep your eye on the ball—and use a fast shutter speed to freeze the action when the ball comes off the racket. (Note the intensity in this player’s expression!). Photo by Mason Resnick.
The volley is more challenging to photograph, as the players are moving around. The key for photographers—as well as for players—is to keep an eye on the ball. Focus on one player, and wait for the ball to come to him. Use focus tracking and a fast shutter speed, and burst mode if necessary. Sit at courtside, near the net if possible, so you can easily switch from one side to the other. Use a zoom lens; 70-200mm on an SLR is ideal.
BAM!: While this was shot in the U.S. Open, getting the ball in contact with the raquet takes practice and timing; practice close to home first. Photo by Mason Resnick
Overhead smash: You may not have too many occasions to get an overhead view of a tennis game (in this case, it's Maria Sharapova at the 2011 U.S. Open, shot from the roof of Arthur Ashe Stadium) but if you're lucky enough to get the chance—or you end up in the nosebleed section of a major matchup and have a high angle, look for lines and patterns that will make the shot a graphical grabber, and use a good, long tele lens (this was shot with a 300mm and cropped for impact). Make sure the ball is in the shot! Photo by Mason Resnick
Money Shot: I was fooling around with an art filter on an Olympus Pen Mini at the 2011 US Open and grabbed this cool moment from the photographer's dugout right at courtside. You can get this close...and this low...shooting at a less busy outer court during a major tournament and nobody will hassle you. Photo by Mason Resnick
The great thing about Tennis is that if you go to a major event such as the U.S. Open or even something more locally, if you stay clear of the key matches there is plenty of action on the side courts, and you should be able to get as close to the action as the pro photographers. In fact, in less important matches on side courts you won't have to jostle with the pros to get into good position courtside. The winning shots you capture may be worth the price of admission!