First and foremost I believe you have to know your goals. Heres mine:
1. I do this as a hobby. So I don't have time to do "media blitzes" and I don't care about getting "signed".
2. I don't care about the money. Some would be nice, but it's more important to me that I get heard than anything.
3. I want to get it out there beyond "make a CD and post about it on facebook".
4. I want it to be a reliable form of marketing rather than fad based, meaning I don't want to have to latch onto the next social or meta networking fad and add a bunch of people to have it fall flat and do it over again in 5 years.
Given that, what's out there that's reliable, that will get me to a wider audience and be more worth my time than hype marketing? is it worth setting up a Last FM page? Should I send to online radio stations etc?
My main goal here is sustainability.. Bueller?