Perfecting Your Ball Toss
One of the keys to a consistent serve is a consistent toss. You can improve the placement of your toss by releasing the ball from your fingertips rather than the palm of your hand. This should result in greater control of the ball toss – a simple way to test this is to check if there is close to no spin on the ball.
To ensure you are releasing from the fingertips, place two balls in your hand, go through your entire service motion, and simply toss the ball positioned in your fingertips. A consistent routine with no tension, combined with a smooth rhythm on the toss, should results in a move consistent action and serve.