Maintain the right form—Serving for a long period of time may allow a person to develop his own form. But as a player takes a week or two off, they may start to forget their form. This will cause a problem in your serve, not only will it change the accuracy and power on the serve, but it will also break down your mental game.
Realize which type of serve you want and stick to it—This is a big problem for many people currently playing tennis. Perhaps one day they feel as if they would like to learn a flat serve, while the second day, they want to learn a top-spin serve. The maximum number of serves the server should focus on, is only one at a time. If you work on more than one serve at a time, chances are that both types of serves will not be trained to their full potential, and you will be stuck with weak serves.