Internet - sort yourself out a website or a myspace account to start with. you can post your flyers on there and just befriend people who may a)go to your gig and b) spread the word.
Gigging in the right places
Brilliant Marketing
Get yourself noticed locally - which may mean you might have to play for free say at a school charity event or something, make sure you get in the paper because:
"Labels can pick up bands that have already built strong plots at press and specialist radio. Why would they sign a band that is completely cold and start from scratch? "
James Roberts, Music Week magazine
What is the name of your band? And where are you based?