Things I see -
Easy things to change:
1) There is some motion that some wasted/extraneous - like a step back followed up with a step forward into the original position during the toss. These are not necessarily bad to the end result - more that you are adding a lot of complexity that does not help and, at worst, may throw off your timing. Try practicing with your feet set with a wider base before the toss.
2) Toss is too far back - try moving the toss forward
3) Try start with your shoulder turn more so that you get more shoulder rotation during the serve. The toss will feel weird because you will be tossing way to your left. Now, you are pretty much chest forward toward the ball throughout the motion. This means you get no energy from the big muscles in your torso - all your power is coming from the small arm/shoulder muscles.
4) I like your right arm position, relative to your body, because you are keeping your shoulder in a safe distance from your head. However, because your back is straight, that means your arm is out to your side at contact - losing height and net clearance. Try reaching up as high as possible with your racquet, while bending your head slightly sideways to keep that good arm position.
5). Sometimes your left arm/head drop early, leading to an awkward motion - keep that left arm up as long as possible.
Harder things to change:
6) I don't see any weight shift forward and into the ball - i.e., a rock to the back leg, with the weight moving forwarding during the serve so that your body weight is moving into the ball.
7) (Related to 3 and 6) You are basically muscling the ball now, rather than relying on your kinetic chain. You would get a harder serve by relaxing you arm/shoulder muscles until the instant before contact. Let your arm go long for the ride provided by your body motion until right before contact and then engage those muscles
Last edited by Nellie; 12-17-2012 at 01:48 PM.