If it looks crappy and amateur, so do you. You know who your potential audience is-it s your job to go to them. You have to create name recognition. Set a goal of 50 posted fliers, and pick 50 good places to hang one. Pay particular attention to areas where people linger-such as cash register lines, bathrooms, etc.
Handbills are also effective.
Go down to the entertainment district on a weekend night and give them to people. Tell them something about yourselves. Be quick, but establish some sort of personal rapport if you can. If the weather s nice, you might even take a guitar and play some of your songs on the street while another band member distributes the handbills. An added bonus of handbills is also that you can stick them on parked cars windshields.