Most high schools have a ladder system. You challenge and beat the person above you in the preseason, you take their spot. Similar to wrestling I guess. Tennis is a great lifetime sport and a good outlet for competitive kids who have found political road blocks in team sports. Btw, if you choose this route, check with the high school coach how they seed players. During my daughter's senior year, the new coach did away with the ladder and brought up all the younger players who played in USTA tournaments. Thankfully, he got fired the next year, but it wasn't in time for my daughter who had been #3 singles the year before on a state champion team and was relegated to a doubles team with another senior that ended up not even getting selected to compete in districts. Lots and lots of horrible people coach