Only 10%? You're cutting us out, man!
Seriously, David, I was once in your shoes: mid to late teens, talented, eager, experienced (we're talking the 80's here -- experience met having had a PC for longer than a year). I tried shopping my skills around, but no one would take me, really. Why? Probably because its hard for "us" adults to trust that a kid is going to be responsible with our computer, our data, etc. Companies are even less likely to allow such a thing.
If you have a mentor to guide you that is willing to take you on as some kind of apprentice (think a small business or ISP or web hosting outfit), you can go far.
Alternative to that, if you have a select number of very happy customers, for instance, from the neighborhood, chances are they work for someone (or own a business) that would be willing to take you on in some kind of intern role. Build this neighborhood clientele via your parent's friends (or your friend's parents). In the latter approach, Linux is not terribly well known, but guess what is: wireless networking. You could offer to install/upgrade people's home networks. After you have ten or so very happy customers (make sure they are VERY happy), ask around if they know if their company has any unix servers. If they find out they do, ask if they could introduce you to "their IT guy".
Here's some things to do with home networking:
- Position and mount routers for optimal location
- Enable strong encryption on the wireless network; use your linux laptop (or linux live CD) to demonstrate exactly how long it takes to break in using WEP and how someone can steal their browser's login sessions and get access to whatever.
- If they have a wireless router that can be upgraded, offer (if this is in their best interests, and after you've tested this yourself 5 times) to install a customized firmware.
- Ask them if they have done their backups lately, and if not, offer to install some free backup software and to train them how to do it.
Before you set out, practice, practice, practice. Reinstall Windows/Linux several times till you start doing it in your sleep. Also, remember to shave both whiskers and get a good haircut. (Tie is not recommended, but a clean, collared shirt is.)
Also, yada yada, good manners, politeness, yada yada.