If only @drmike were here, since he taught me a ton and really deserves some credit. Well, here goes a list, in no particular order:
Social Media Marketing (SMM)
Email list marketing (mind you, this is not the same as shotgunning the same deals out to your email list every week and waiting for unsubscribes)
Affiliate marketing ($$$$-$$$$$$)
Guest posting quality content on industry blogs
News write ups
Find the ways that you would like to market, make sure that they fit into your budget, and then continue with them. No single marketing scheme should be one-pronged, and you should carry out your marketing plan remembering to sow your seeds every day, and eventually you will have something.