As for how to get into the business... I posted a submission on a popular (Russian) programming site offering Ruby and RoR lessons. 2 years later my post is Google's search results first page. Then I started doing Ruby and RoR screencasts in Russian, they became #1 in Russian. That brings even more people. It's not a lot of money, mind you, but at some point I even quit my job completely and went to Thailand for 6 months. I'm thinking of stopping doing it, because frankly, I'm just tired of teaching. For now.
I wanted to make more money. So it was really selfish. And I wasn't good at teaching right away. What kept me on the way to improvement is also money. I knew that if I don't provide value to my student, he'll leave. If I act like a jerk (trust me, such a temptation sometimes), he'll also leave. So I just did the best I could to keep earning the money.