Once you are a recognizable name on the internet then you need to start working on your relationships with the music promotion channels. These guys are pro music fans who are devoted to playing new tunes that need airtime, and often they will stick to a single genre or two. Research each Channel and see what their style is – don't blindly send off your tracks.
Choose your audience and start following them. Music Promotion Channel owners are far more likely to play the music of someone who has been following them for some time or who actively supports them in online forums. Show them some support and back it up with a little friendliness.