I have great success with Facebook, not my business page so much but with my personal page.
Most of the 638 friends I have on there I actually know, I spent Ten years on Corfu - went to a few different schools, have done a few long term courses, was a sound engineer, ran a bike club etc so I have done a lot of things which exposed me to a lot of people - they found me and befriended me on Facebook.
So, that way I have a list of potential customers who all WANT to be on my list - all I do is post images of things I have done and they share them ! it's perfect, THEY do the promotion for me and I get work from it.
What I would recommend avoiding though is putting all your eggs in this online basket as you will end up spending ALL of your time online - I was in that situation a few years ago with a Lottery Business I was promoting and I certainly do not want to be in that situation again.
It is working for me, and I dont try really - just want to show my friends what I have made as they are genuinely interested.