Looking to build your interior design business? Look no further than your current clients.

After all, your current clients are your best ones. They’re the ones who know, trust and value you. They’re the ones most likely to refer you. And they’re the ones as interested in forging lasting partnerships as you are. Perhaps more so.

They’re looking for a professional they know and trust to handle their future challenges. They know it is less time-consuming and expensive to develop a lasting relationship with a single firm. It’s in their best interest, as well as yours, to develop long-term relationships.

The problem is most design professionals fail to tap into their resources of clients as much as they could, or should.

They fail to inform them about all their services and, as a result, they lose out on sales. Leaving money on the table, in fact, is one of the major financial challenges facing interior design pros today.

You can overcome that challenge and maximize your current client relationships by promoting all that you do, and using strategic upselling, cross selling and add on selling of your additional services.

Asking current clients about future needs can unlock numerous opportunities and substantially boost sales.

Ask: "What about…?" questions. No question leads to more sales than one with those two words. Ask: "What about the kitchen?" Or: "What about your vacation home?" Or: "What about new furniture for the regional offices, too?" Or: "What about having us redesign all your hotel lobbies?"

Many clients have other needs. What they don’t have is knowledge that you can handle them. That’s why it makes sense to promote your full-service capabilities — in person, and in all of your marketing materials.

Clients may be clueless that you also work on entertainment centers, or wine rooms, or outdoor kitchens, or corporate offices. Tell them when you pose those “what about” questions. And tell them as you ask about "Phase II" of the current project. Or about upgrades.

"What about" questions work wonders. They set the stage for additional sales and ongoing relationships, and get clients thinking about what to do next as well as what to do now.

One of the most successful window-covering dealers I know is primarily a floor-covering dealer. When measuring for carpeting, he asks: "What about the windows?" He sells a lot of window treatments that way.

There is enormous potential in discussing your additional products and services. Think of fast food chains, which make millions of dollars of additional revenue each year at the drive-through window by asking customers if they want to add fries or a drink to their order.

Your current clients are the ones who can boost your bottom line over time. The numbers bear that out.

A repeat customer spends an average of 67 percent more than a new one. The long-term value of each client is over 100 times the value of a single transaction. The cost of retaining an existing client is a mere 20 percent of what it costs to attract a new one.

Management consultant Peter Drucker estimated that the average company has a 1 in 14 chance of doing business with a prospect, but a 1 in 4 chance of working more with a customer.

Appreciate the value of your current clients and go above and beyond the call of duty to meet their needs. The better you serve them now, the better your chances of serving them in the future — and reaping the rewards that come with repeat business.