Originally Posted by boramiNYC
Know how you use your core. Do you rotate and or bow/arch your body and how much for each. Mostly some combination but it's good to know how much of each you like to do and can do. This affects the precise feet positions and stance. try not using the torso rotation and bow at all and just use the shoulder and arm for practice. face forward to do this. only when your torso is rotating turn the stance sideway. strong full 90 rotation full sideway. relaxed smaller rotation less sideway, etc.
Let us pause right there. I am very particular about serve and constantly tinkering with it to get it like the pros. I have even stopped playing if I felt unhappy with the serve, just not returning the returner's return.
What is a realistic speed expectation when using only shoulder and arm?