Profit Kids is a blog that tells kids under the age of 16 how to make money. These are not just the obvious ones like "make a lemonade stand." They are great and effective ways to make money and are not hard. Be sure to check back often because new ways are added all the time!
Start a club like a chess club or a dance club or a parkour club or something like that. For people to join it, charge something, but not too much. And be sure to make sure your club is fun and interesting. Meet at least once a week.