You can practice the toss without leaving your living room. (Ryan Loco)

The serve has more moving parts than any other stroke, so it can be easy to get caught up in its minutiae. Of them all, the ball toss is the most crucial component. A bad toss can ruin even the best service motion; a good toss can hide or fix imperfections, and help you make proper contact.

You can improve your ball toss from almost anywhere. Sit on the edge of a chair or couch and turn your body so that you’re sitting at an angle, like you would stand at the baseline preparing to serve. Your front foot should almost line up parallel to the couch or chair. Extend your hitting arm fully and point your racquet straight up to measure how high you want to toss the ball. Aim for just above the top of your racquet.

The same way there is a technique to the swing, there is a technique to the toss. Your tossing arm should be straight, and the ball release should be around eye level, which will help your consistency. Start your tossing arm lined up with (or on top of) your front thigh. The tossing arm starts the body and shoulder turn; you don’t want to flip the ball with a bent arm, or release the ball from too low. Hold it loosely with your fingers.

Practice a couple tosses with a ball, or even rolled up socks, to gauge the height of your toss. If you hit a standard-height ceiling, you’re tossing too high. Hold your finishing position on the toss and let the ball or socks hit the ground. If you can keep your arm straight and release at the right height without hitting the ceiling, or the ball being too low to hit with a racquet, you are ready to move on.

Next, place an empty box just along the outside of your front foot. This is where you want the ball to land. When you toss, keep your non-dominant arm up after you release the ball, and keep your body still. The ball should land inside the box—which, if your body has not moved, is just to the left side of your left arm. It means your body is turned, and will be ready to rotate and transfer energy into the serve. The rotation allows your body to transfer power from the ground up, and takes stress off your arm.

Test yourself and see how many tosses you can make into the box in a row, or how many out of 10 you can make in a set. Work on this drill at home and you’ll develop a serve you can count on when you return to the court.

Marc Lucero is a professional coach based in Manhattan Beach, Calif. He currently works with Steve Johnson and Nicole Gibbs, and has previously worked with Shelby Rogers, Alison Riske and Eugenie Bouchard.