I worked fixing PC on the side since I graduated college.
Pros: easy to work around my schedule
Cons: not a lot of repeat business, didn't make a lot of money.
People would call and tell me their problems, most of the time I would go over and fix the problem at their house unless it was something time consuming then I'd take it home with me. I'd educate my clients on what they did to get like they were and show them how to not do it again.