I haven't really realized this but video taping your serve from different perspectives really help out on deciphering the problems with your serve technique. For anyone, who needs improvement on their serves, take a video of it and compare it to professional level serves and see how your technique differes from theirs. It'll also help if you have a slo-mo video camera. It'll really help. Just a little tip that I figured out but probably a lot of ppl already knew. Anyways, try it out if you havent.