Listen to LeeD about using your body motion to start your serve, just like Fed and all the pros.
Look how far Roger leans in to start his serve. That is not just wasted motion. That is starting to use a big body motion to start the serve sequence, just like you would use a big body motion to power your strokes.
Notice in pic 1 above, Fed has leaned into the court with his upper body.
He uses the momentum from leaning back from this initial lean in to not only get the serve started, but to set to the tempo of the serve.
Lean back fast to the position he has in pic 2, and you will likely bring the tossing arm up fast.
Lean back too slow to the position he has in pic 2, and you will likely bring the tossing arm up too slow.
Lean back at the proper speed to the position he has in pic 2, and you will likely begin to raise your arm at the correct speed.
That is because most of the movement of the tossing arm from pic 1 to pic 2 is not from raising the arm, but merely from changing the shoulder angle.
(In pic one the front shoulder is much lower than the back shoulder - but by pic 2 the shoulders are level.
Achieving the right tempo of your whole toss sequence is very important as emphasized in this video by Brent Abel:
Tennis Serve Tossing Motion Tempo http://www.youtube.com/watch?v=CeZp9...feature=relmfu
For more tips on how to have a great toss, check out these threads: