You volunteer for something, or join clubs out of school, play a sport out of school, join a certain camp or something.
You can try going to your local rec center, go to the mall, or to a favorite place where you like to spend time and see if you can find new people there.
I usually meet them either through friends, on facebook, at the downtown mall (probably not where you live) and just random person. You just need to talk and make conversation.
church group, social places, take ur friends from ur school and go people shopping
get ur friends to introduce u to other ppl from different schools
come to play to your friends house and let them introduce you to their neighbors, cousins, brothers, sisters...
Get your friends to show you around hang out with them and meet other people,
Go to Places that interest YOU!! Then work your way from there.
Youth group there are always Cute girls/guys at youthgroup
Go to main hangout places. Like the mall or park.
meet ur friends friends... go out... mingle!
parties, mall, park, x)
Fun advice of course!