My entrepreneurial journey has seen me start and exit four companies, one of which, my research business, was acquired by a public company. My new book Built to Sell: Creating a Business That Can Thrive Without You is being released today and to celebrate, I want to share three of my best tips for building a valuable – sellable – company.

Tip No. 1: Slay the Elephant

It's common for a business to be dominated by one or two important customers. It happens pretty naturally. You do a good job for one customer, and they buy again. You keep satisfying them, and they stop looking for other suppliers and start to bring more and more of their orders to you in hopes you can handle the increase in business while maintaining your amazing service. 

Given their importance, you're probably also servicing this giant customer personally, which makes them even more profitable because you do not need to hire sales or service staff to support the account. This, of course, makes both the account and your business very profitable—which makes it harder to walk away. It's a cash cow.

Pretty soon, you have a codependency that can undermine the value of your company—and make it virtually impossible to sell. For example, an acquaintance of mine owns a business that supplies a product to the home improvement chain Lowe's. In some months, Lowe's makes up more than half of his revenue, which is why, when the U.S. housing market crashed and Lowe's slashed the size of its orders and slowed down its payment cycle, my friend's business teetered on the brink of insolvency.

Desperate for cash, my friend tried to sell his company to both strategic and private-equity investors, all of whom offered him pennies on the dollar (when compared to the value of similar businesses) because of his reliance on just one customer.

To build a valuable company—one you can sell if you choose—you need to winnow down your reliance on any one buyer. My suggestion is to strive to ensure no one customer represents more than 15 percent of your revenue.

Tip No. 2: Sell Less Stuff to More People

We survive the early years of our business by listening to our customers and responding to their requests. The problem is, when all you're doing is reacting to customers, you end up offering way too many things—customizing too much—because everyone wants a slight twist on your offering.

If you offer an ever-expanding list of things, your staff will never get really good at making or selling anything. The broader your product or service line, the more your business will be reliant on you—the person with the most knowledge in your field—rather than your employees. If the business is too reliant on you personally, it will be hard to sell.

To pull yourself out of this quagmire, you have to sell less stuff to more people. That may seem like counterintuitive advice, but some of the fastest-growing, most valuable companies in the world do it.

Take Apple for example. Apple is really good at selling a few core products (iMac, MacBook, iPhone, iPod, and iPad) that offer the same basic user interface. As a result, the company can train its Apple Store employees on one basic operating system and a few core products.

By contrast, walk into a Best Buy, with thousands of technology products running hundreds of different operating systems. If you're actually able to find someone to help you, you'll be lucky if they can read the specifications on the back of the box, let alone actually know anything about the product.

Focusing on selling less stuff to more people will allow your business to scale up beyond you, which in turn will allow you to grow through the ceiling that holds back many owner-dependent businesses. Ultimately, you'll have a company you can sell.

Tip No. 3: Stop Grovelling for Work

Quick—how do you explain your business in a social situation? Do you define yourself by your industry? For example, "I own a printing company." Or do you describe what makes your business unique? For example, "We've developed a process for printing annual reports that reduces the turnaround time to three days."

The problem with describing yourself as a part of an industry is that most industries are commoditized. You're sentencing yourself to a life of low margins and groveling for work. When there is nothing unique about your business, the customer has no choice but to rely on price as the only decision-making criterion.

And before you claim "customer service" as what makes you unique, remember that people don't buy wishy-washy claims as a point of differentiation. After all, service is in the eye of the beholder, and until your prospect makes the decision to become a customer, intangible claims about how well you treat your customers ("offering great customer service since 1977," "specializing in great customer service") will not sway them.

Instead of describing your business in terms of the industry you're in, accompanied by some vague description of your service, describe in concrete terms what makes your business different. For example, under Tony Hsieh, Zappos became a successful company (Amazon acquired it in 2009) not because it's a retailer of shoes but because it offers a two-way free-shipping policy.

One-way free shipping is standard for a lot of e-tailers, but Zappos offers to ship your shoes free and then if you don't like them not only refund your money but also pay to pick them up. "Great customer service" is a wishy-washy claim. "Free returns" makes Zappos special and is a big part of what sets it apart. A shoe retailer is a boring commoditized business with low margins and very little hope of being acquired. A company that allows people to return shoes if they don't like them, all from the comfort of their own home, is unique and a big part of the formula that allowed Zappos to scale up into a sellable business.

Stop describing the industry you're in and start describing what makes you irresistible. 

Order John's new book Built to Sell: Creating a Business That Can Thrive Without You by April 30 and you'll get this $65 basket of thank you goodies.