How can I get more velocity on my serve?

If you aren't already, you should try to use the Continental grip (like you are shaking hands with the racquet face vertical). This is important because for the control aspect of the serve, if you hit a serve harder, you need more topspin (generated from the Continental grip) to keep the ball in the service box. Start with a higher toss (one that you can hit at its highest point) and try to place the toss a few inches in the court and a few inches towards your serving hand, so you are aren't restricting your motion by having to reach back over your head.

For the service motion, take Andy Roddick for example, he has a considerable knee bend to generate upward thrust as he springs up at the ball and he brings his feet together before he makes contact with the ball. Other great players use a large shoulder turn (for a more exaggerated shoulder turn watch Pete Sampras) to generate more power. The hard part about the serve is the timing of every small aspect. It definitely takes a lot of practice perfecting every aspect of the serve but it is one of the most important shots because it starts every point! Good Luck!

Roddick Serve (found on YouTube, kind of grainy) - http://www.youtube.com/watch?v=hi9nQPAZ3SM

Sampras Serve (also found on YouTube) -http://www.youtube.com/watch?v=XqocgyLYofs

Well when ever you go up to hit the ball make sure u toss it high enough, most people say high above your head but i usaly do a few inches above my head, but its not on how hard you hit the ball, its about how quick you hit it, make sure you make contact with a quick motion, don't worry about how hard. Finally, make sure you follow through, if you do not do this, everything else is a waste, good luck, o yea, u have have to practicve it alot

When you go to hit your serve, extend your arm and jump. Just make sure that it doesn't reach the outside of the baseline. Gain some more confidence in your serve!!!!

Well, you can only get more consistent when you practice your serve....and keep doing that. But you need to hit the gym and beef up a bit if you really want to put some umph on that serve.

Your serve power comes from your legs and not so much the arms. Try jumping into the serve and you should get more power

try hitting ur first serve flat and toss the ball up high over your head. If that doesn't go in try put spin on ur second serve (topspin or slice)