I've been tutoring for over a year now, and lately, have been trying to tutor more than just C++. Specifically, I want to try helping people out in using the Windows Operating System, Microsoft Office products, etc...
For sure! Besides craigslist posting at your local library, old-folks center, and other public places are great. If you get the opportunity to teach a continuing education computer class you can get quite a number of clients from there. Making friends with your local repair shop to swap services is also a good idea.
If you live by a university, talk to the computer science department, though they might want you to go through official channels.
There are many services online that do tutoring type things for a cut, two that come to mind immediately are wyzant.com and takelessons.com
You have tons of sources, just get out and socialize with people, if you treat it like a business you'll have success.