Here's what I do, and what you should do to get some good business. If your parents have one of their friends over, steer them into the direction of computers, and they'll mostly say "OH MY (son/daughter) GOES ON THESE STUPID SITES AND DOWNLOADS A BUNCH OF CRAP NOW MY COMPUTER IS SLOW!"
That's where you get the paper. Sometimes in my case I'll be like, "I can build you a nice decent computer, just tell me what you want in it and all you'll have to do is pay for parts and labor."
Over the past 3 years I've made about 2 grand just in labor to my parents friends. It's really simple because they're really computer illiterate and say "OH I DON'T WANT NO FANCY stuff." so I get about the cheapest parts.