Rather than cold-calling new customers or flogging weak ones, good salespeople understand their best bet is to focus on reselling to their best customers. But there's another way to make the most of those great customers. Invite them to be on your new advisory board. Their role? Once or twice a year, invite them to a lovely lunch meeting in which you solicit their suggestions for augmenting your business. They benefit from the good lunch and prestigious "board of advisors" title, and you get valuable input plus increased loyalty - if a customer joins your firm's board, he's less likely to switch vendors.