The beginning of the school year is the best time to join most clubs, with the exception of sports which begin during different seasons. You won't have trouble finding a club that suits you since most schools have many clubs. If you can't find an existing club that suits you, don't worry. You can try starting up a new one with a teacher sponsor. Most schools have a few basic clubs, which include student council, annual, and newsletter club.
Clubs can also include sports.
Many schools have sports teams like bastketball, soccer, volleyball, hockey, track and field, and football that play against other schools in their area. Many people will be interested and will join in.