Almost as long as I remember I have always carried a camera. 2001 I bought my first video camera. I didn't go to any film schools or read any books, I just started filming and editing. After a while somebody paid me a small sum and I had made my first money! Now, 2014, video jobs account for about 1/3 of my yearly income. I don't do any kind of marketing, it's all word of mouth. I have from time to time tried to marked myself but it has never led to anything.
All my own documentaries so far have been self financed, zero budget projects where I take care of everything. Camera, sound, editing...whatever needs to be done. I'm making very little money from these films but I wouldn't like to work any other way. It's complete freedom.