The key to a powerful serve is a smooth motion. A hitch in your swing impedes the progression of your arm and makes it more difficult to generate service power. To ensure a fluid motion, envision the pendulum on an antique clock. Notice how the pendulum swings effortlessly back and forth. Your racquet arm should swing down, around and then up to hit the ball with the same rhythmic motion. By maintaining flowing momentum on your serve, you will be able to maximize power. Incorporate the rhythm of a clock pendulum for a smooth service motion that is right on time.