What I've seen work:
Use BreakingTunes. It's VERY important for all bands to be on this nowadays, it seems.
Contact Nialler9, Nay (on Entertainment.ie) or Darragh McCausland (Asleep on the Compost Heap) with your demos. They have big audience and have helped break lots of upcoming Irish bands (Adebisi Shank, ASIWYFA, The Minutes...etc, etc)
Get some good images. They're the first thing people will see. I know it goes against what you think - but you need an image these days as much as you need good tunes.
Good posters - get noticed when you advertise what you do. See Popical Island's posters. Eye-catching and doing a good job.