Write "Nekrogoblikon" in your forehead and run nude in the streets (?)
Speaking seriously, you should try to contact the under radio and newspaper of metal from your zone, thats a very good way to make yourself a promotion.
Also you could fotocopy a few flyers saying that "you're going to *play on x at x hour x day* and you make the best goblin kickass metal* and ask to the people in the metal and rock stores if they let you to put it in the door, stand, near the shirts or something. If they say no, just stand in front of their doors and give it to every person rocker/metalhead who enters to the store or just passes by there. If you don't have time to do that, you could pay a few bucks to a little neighbour or somebody.