I'm a 4.0 woman, and I hit mostly slice serves for first and second. The reason for this is that the spin confounds many people, the ball stays low, and many people will struggle to attack a slice. Recently, I have added a topspin serve, which is a nice changeup and is good for dealing with people who figure out how to handle the slice. I rarely hit a flat serve because most opponents are quite capable of blocking back even the fastest serve I can produce. Spin works better. But enough about me. Here's the problem. Every now and then, I produce a serve that I didn't intend to produce, and it often goes for an ace or service winner. Sometimes it is a deuce court serve that lands close to the net near the sideline. Other times it is an ad serve that hits the middle of the box and just dies there, with the opponent lunging forward and popping it up or netting it. I would absolutely love it if I could produce these serves on demand rather than being just as surprised as my opponents. Apparently, I do not understand what is causing my serves to behave in this fashion. What is the mechanism that allows you to hit the front corner of the deuce service box? What am I doing that causes a serve to hit the court and die? How can I learn to produce these serves at will?