Your medium- or small-business can live or die by its marketing. One of the greatest angles costs you no capital. Establish yourself as an expert in your field by offering advice through websites and magazine trade articles. Readers will migrate to your business, and you can point potential customers back to the articles for an extra marketing push.
To get the best results, find publications and topics that fit. I know a therapist who has written about meditation for spirituality and yoga websites. He uses mindfulness in his practice and has built up a stream of clients who have found him through those articles. Consider these tactics for nearly any other service-based business.
You can get similar results--but it can take more work--building up your own audience. Many, local real-estate blogs, for example, give details about market conditions in a specific area. If the content is good, offering home-buying tips and tutorials, readers will associate that help with the author. If that author leaves a blurb about their day job, readers will seek them out.
In either case, be an expert about your industry, but don't shill for your business. Readers see through any overt selling. The real marketing comes after you help the readers and they seek you out. Make the connection then, and they'll see you as an expert, not a pitch-man.
Zack Stern is building a new business from San Francisco, where he frequently contributes to PC World.