Whether you are practicing your ground strokes, volley, or serve, the key to improving any aspect of your tennis game is consistency. This is especially true when it comes to the serve, as a player with an inconsistent serve has lost half their games before they have even begun playing. Developing a consistent serve that lands over the net and into the service box is the first step toward improving your overall performance on the court. From there, you can further develop your serve to become a powerful weapon.
The most important factor when serving is the toss. How high you toss the ball, its position in the air with respect to your body, and how much it rotates (if at all), will all impact where and with what amount of force the ball lands.
Generally, a higher toss will be more effective, but you don’t want to toss the ball too high, where it will be at the mercy of the wind and you will lose some level of control. The height of your reach with your arm fully extended should be the height of your toss. If you choose to jump to generate more power, your toss should accommodate for the extra reach.
Your toss should be out in front of your body where it will be easy to keep your eyes on the ball, reach forward, and follow through. Whether you jump or simply step when you serve, you should be moving forward, into the court, so that you are better prepared for the next shot. A toss that is in front of your body allows you to maintain better footwork and uses your bodyweight to generate more power and control as you follow through.
The third element of an effective toss is the ability to remove spin from the toss. While adding spin after contact can make the serve much more difficult to hit, the same is true if the ball spins when you toss it. However, in that case, you will be the one to lose some degree of control and a much larger degree of consistency.
If you are standing correctly, you should be able to draw an imaginary line from the toes of your back foot to the toes of your front foot to the far corner of the service box. To practice your toss, line your racquet up with this imaginary line and place it on the ground so that the butt of your racquet touches the toes of your front foot. Hold the ball in your first three fingers (or hold two balls in your hand and toss from your fingertips), stretch your arm out straight without bending your elbow and toss the ball. Your goal is for the ball to land on the face of your racquet. Doing this exercise repeatedly will show you how consistent your toss is while also improving it.
For most people, a continental grip is most appropriate for serving. This means that when you hold the racquet straight out in front of you its face will be perpendicular to the ground, as though you are shaking hands with it. With a continental grip, you can comfortably grip the racquet when you serve and are better able to control your placement of the ball. However, by rotating the racquet to a slight backhand grip (for right-handed people, a slight turn to the right), you will be able to angle the ball more effectively. A backhand grip will allow you to put spin on the ball and place it into the corners of the service box, making your serve much more difficult to return.
To get accustomed to a new service grip, try placing a towel or sweatshirt on the ground and serving from a kneeling position. If you are altering your grip, position, toss, or all three, serving from your knees will force you to apply what you have learned. Start with your racquet behind your head and serve just as you would standing. You will keep your head up, toss the ball higher, and be forced to stretch your arm out straighter. You can then apply these elements to your usual serving practice as well as during matches.
