The second and third areas of growth discussion are extra hip and shoulder rotation. There are 5 tricks to get extra hip and shoulder rotation. A. move your back foot to the toe area of the front foot and pull back on an slight angle toward the ad court side. Turn that foot's toe out toward the back fence. These 2 tricks automatically give you the 3rd trick of more shoulder blade rotation.
Some pros circle their arms to build momentum on the rotation.
Becker did this. Agassi is the most visible pro doing this currently. The last trick is that when you land you spin on your front toe . This is tough to pick up on t.v. as the camera is off the server feet quickly. You need to see this in person to get this.