Well first step is to find out the local tournaments, and get a rundown of the level of the tournament, and then plan ahead and apply to whichever one you think you can fit into your schedule. Start with district level tournaments, and if you stack up a lot of points try to get into sectionals, and even nationals if you are good enough.
Also find a tennis welcome center because they generally have very cheap courts, so you can perhaps find a partner of equal level and split the cost of the court so you can practice outside of tournaments.
"I got dosed by you and
Closer than most to you and
What am I supposed to do, take it away ."
-Red Hot Chili Peppers, Dosed