Go to tennis courts that have walls to hit against. Find a bored person using one, or use one and look around, looking bored. Try college campuses. Look for groups of 3, they might play doubles or split off to play singles. Go to a bar and look as if you are on the prowl. Ask women if they play tennis and try to make arrangements to play with them instead of trying to pick them up. Some will be so shocked, they'll say they play even if they don't. A group of my friends and I figured out that this...Oh, yeah, looking for a tennis partner, started to wander off there. Good luck.
"In theory, there is no difference between practice and theory. In practice, there is." Lawrence Berra