When I was 16 in highschool, I started a Mac Onsite repair/consulting business. I designed a website and got my name out there with small businesses and contacts through friends and family.
I charged $30/hour, and often time got even more (tips). If you act professional, nobody will question your age. Just get your name out there.
I'm a few years older now, and I carried my business and business name up to College. Got a few small businesses to hire me, and now I charge $40/hour, and work oftentimes 10-12 hours/week. Basically pays for school.