Expand geographically, not demographically. If you do business with medical doctors in one location, it's easier to find doctors in another community than it is to try to sell to dentists in your home territory. Once you've built a rapport within a certain customer community, your reputation will make it easier for you to sell to like customers in other areas.
This type of approach simplifies your marketing and sales efforts. For example, if a doctor in Chicago knows that you've sold your product or service to hundreds of doctors in the tri-state area, chances are he or she will place more trust in you than if you've sold only to dentists in a single city. Selling to the same type of customer increases your chances of capitalizing on word-of-mouth and referrals.
Excerpted from 303 Marketing Tips Guaranteed to Boost Your Business