Now that the weather is warming up, I was thinking of spending the spring/summer learning another serve. Right now I can hit two types of serve. My main serve is a slice. I can hit this serve pretty well and it serves me well in matches. It wins me lots of points early in matches, but my opponents often adjust as the match goes on. I can also hit a flat serve, but it is nothing spectacular. Mainly useful for serving to the body when people figure out they should stand closer in anticipation of the slice serve. I find I have a hard time toggling back and forth between the flat and slice serve, however, and am likely to start missing my flat first serves under pressure. I kind of get used to the slice spin keeping the ball in, so trying to hit flat starts to feel low-percentage. OK. I'm thinking I need one more serve to be able to mix things up a bit better. Every now and then, I hit a twist serve by accident. I hit one last Saturday to a pretty good 3.5 teammate, and she actually caught the ball because it jumped in a direction she wasn't expecting. I thought, "OK, that's cool. I gotta learn to do this, so when I alternate between twist and slice people will get dizzy and fall over." Then again, another teammate thinks I should learn a topspin serve because she finds this useful for serving to the backhand because it backs the opponent up. Then again, my pro says to forget all this stuff because my current serve is plenty strong for my level and instead work on the many other weaknesses in my game. He thinks I will just hurt my back trying to hit a twist serve. This advice I will blow off, of course, because I am extremely hard-headed. So. Which serve should I learn? Which is easier and more reliable under pressure and best suited for the game of a 3.5 woman who plays some mixed and mostly doubles?