Making the first sale to a customer is very expensive. It takes a lot of advertising and promotion dollars -- and a lot of time, energy and money chasing dead ends -- to land a customer. Yet subsequent sales to that customer are relatively inexpensive -- and profitable. Too many businesses make the mistake of focusing on generating more sales to first-time buyers -- rather than working harder to build sales with the customers they already have.

With first-time buyers, you not only have the costs of getting that first order, but you still have to build a foundation of mutual trust if you hope to get follow-on orders. With your existing customers, you've already built this foundation of trust -- you only have to maintain it -- by continuing to deliver quality products and service. Cultivating broad and deep relationships with your existing customers allows you to focus your limited resources wisely -- building as great a share of their business as possible -- while your competition fights tooth and nail just to get their foot in the door.

This customer-driven (versus product-driven or technology-driven) strategy goes by many names: Relationship Marketing, Retention Marketing, Frequency Marketing, Loyalty Marketing, Frequent Customer Marketing, etc. But whatever you choose to call it is not nearly as important as your understanding that your existing customers offer your greatest profit potential.

Here again the old "80/20 Rule" applies: In an established business, 80% of your sales come from 20% of your customers. These are the customers to focus on. If you don't know who they are -- if you can't list them -- in order of decreasing sales -- find out. Analyze your sales and make a list -- and hang that list where you can see it every day. And every day, ask yourself, "How can I build my sales with these customers? How can I strengthen my relationship with them?"

Here are some suggestions:

• Look for ways of maintaining an on-going flow of information with them. Think of them -- and try to get them to think of you -- as a "business partner". Personal phone calls... Visits... A customer advisory council... Etc.

• Make the effort to learn their business so thoroughly that you can initiate new areas of business activity between you and them that can profit both of you. If there's a product or service that's giving them grief -- or from a vendor they're not totally comfortable with -- try to figure out a way to provide that product or service yourself. Even if it's not a product or service you currently offer -- or had planned to offer. Keep in mind that it's often easier and less costly to add new products/services than it is to add new customers.

• Add additional services -- preferrably unique to your customer's needs -- that demonstrates your attention to the small but important details -- and helps keep your competitor's foot out of the door.

• Think about adding "loyalty" programs where you can reward your customers' loyalty in ways that your competitors can't easily copy.