I agree with Barbara that traffic is the key. How can you get it and sustain it to the masses without being considered a spamster? Some use bots and I'm not certain if that is exactly legal at that site. I know that I've been the target of spam on MySpace.

I'm guessing that the rest is a numbers thing as well. The greater the number of folks that hear your music via your site and check your page out, the more likely that some will like it and support it.