If you put 10 different players on the baseline and have them serve, you will likely see 10 different service motions and serves.
The most common attribute of the best servers is their ability to keep the toss consistently in the same place. This allows the server to swing with confidence and adds smoothness to the swing. The result is likely to be a serve with a lot of pace or spin hit to an area close to the desired target of the server.
Keep the ball in contact with the racquet at the beginning of the motion and try to "release" the ball straight up in the air with little effort. Keep the toss slightly to the right (if right handed) or left (if left handed) and out in front.
If you start your hand in the position I just described and toss it straight up, this should give you the desired result.
Remember, the toss is the most difficult part of the serve and it is the most important. Keep your focus on the toss!
Steve Annacone, USPTA Elite Pro, is the Director of Annacone Tennis (http://www.annaconetennis.com). For details on lessons and camps at Sag Harbor Park Tennis and throughout the Hamptons this summer contact firstname.lastname@example.org or email@example.com