As a teacher, sometimes I'm amazed at the numerous motions and
gyrations I witness servers go through. Regardless of your dynamics, the success of your serve is predicated on having a smooth, slow, and deliberate motion in your tossing arm. But many players fail to note the importance of having a "quiet head" during this process. As they are preparing to release the toss, they tilt their head back and wonder why all the tosses end up behind the baseline.
To help ensure your toss goes into the court (it will go up on it's own), make sure your chin only goes up one or two inches but your eyes shift up to your toss spot considerably.
The farther your chin goes up, the greater chance your toss ends behind your head, which means you will be relying on arm power only, instead of using the transfer of body weight into the serve.
So remember, "shifty (spelled carefully) eyes" instead of a pronounced head tilt will result in a much better ball placement into the court. This is something you can implement immediately without changing your motion (no, matter how wacky it is!) Try it out... I guarantee you will like the results!