Summarize the following:
Most schools host a ton of clubs and activities. Join a few and see which ones you like the most. Try not to over-commit yourself, but have enough variety that you can find something-- and a group of people-- that you really "click" with. Get to know new people in the club(s). At each meeting, try to talk to someone you've never talked to before. If school organizations aren't your thing, find another hobby outside of school. Check the local paper (or its website) for community events nearby. Libraries or art studios often host events for teens. Look for organizations that hold meetings for things that you are interested in, like outdoor activities, games, or artistic expression. This may be a cool coffee shop, a bookstore, a rock climbing gym, or even the mall. If you base your hangout spot around your interests, you're more likely to meet people that you have something in common with. Activities such as football games, dances, or large-scale fundraisers often draw a large number of students with different interests and personalities.
Join a club or activity. Find a social hobby. Hang out where other people you admire spend time. Attend school functions that draw large crowds.