(FORTUNE Small Business) – Making FSB's inaugural list of fastest-growing companies is an occasion to celebrate. These companies are exemplars of imagination, energy, know-how, and stamina. All have sped away from the competition--and have sustained their amazing growth for three straight years. But after the champagne gets uncorked, a few tough questions are worth asking: Can they keep it up? Will they be on the list next year? Or even survive through next year?

For a contrarian perspective, listen to David Birch, president of Cognetics, a Waltham, Mass., research firm that tracks ten million public and private companies of all sizes. Birch loves fast-growing businesses, albeit for a slightly macabre reason. When he sees a company expanding at hypergrowth speed, he often sees a disaster in progress, followed by a liquidation sale and an opportunity to refurnish his offices. "One fast-growing telecom company spent a fortune on furniture," he recalls. "When it went out of business we got beautiful bookcases, chairs, desks, and computers for 12 cents on the dollar."

You don't have to adopt such a buzzard's-eye view of success to recognize an essential truth: The velocity of hypergrowth can sometimes blind the pilot, and when you're traveling at such speeds, losing control can be catastrophic. The bankruptcy courts are littered with former highfliers that have crashed and burned over the years, from dot-coms to brick-and-mortar retailers, telecoms, and even fast-food chains. (Remember Boston Chicken?)

Could any of these companies have anticipated their problems? More important, how can you tell whether your own business is burning itself up, and how can you stop it? To find out, we spoke with dozens of entrepreneurs (including many from this year's list), lenders, consultants, and academics to identify a few patterns of failure. Here, five hidden tricks for how to steer clear of trouble and manage your company's growth the right way.

1 DON'T IGNORE THE DETAILS

Everybody studies the glamorous figures like cash flow and market cap, but how about the boring stuff that only guys with green eyeshades would find interesting? In its most recent quarterly survey of 425 small-company CEOs, PricewaterhouseCoopers asked whether they thought they spent enough time on the job. A surprising 34% answered no. Among the most commonly neglected tasks was keeping a close watch on accounts receivable.

Just look at TSI, a privately owned telecom in Westlake Village, Calif., that provides corporate communications services. In its heady early days in the late 1990s, TSI let receivables sit around for 120 days, creating the illusion of rapidly growing revenues without the reality of cash coming in the door. When it had to borrow to pay its vendors, it discovered that banks wouldn't accept receivables of dubious worth as collateral. "This was a life-threatening situation," says Debbie Ward, CEO. So in 1998, TSI bit the bullet. It wrote off $500,000 in moldy receivables and now insists that customers pay within 45 days. As a result, says Ward, TSI is thriving.

Similarly, Peter Caswell, CEO of Advent Software (No. 16 on the FSB 100), a San Francisco company that develops financial services programs for brokerage firms, likes to roll up his sleeves and get personal with the financial reports. Rather than install himself in a lofty office, Caswell moves to a cubicle in a different part of the company every three months--engineering one quarter, sales the next. It keeps him humble and grounded in the fundamentals of the business, he says. "If you sit in the front office, you might notice in the quarterly reports that sales of a particular product have gone flat in one region. But you don't take time to pursue the second, third, and fourth questions about what has gone wrong and how that might eventually threaten the entire company."

2 DON'T RUSH TO HIRE

A misfit is not necessarily an employee who's incompetent. Rather, it's someone who doesn't function well in your business, because he either doesn't have the right skills or has ways of working that are incompatible with yours. Unfortunately, hiring the wrong person is one of the most common errors of fast-growing companies and perhaps the hardest to avoid. When you double your work force each year, it's tough not to make a few mistakes. They tend to come in two forms: The first is wedging jack-of-all-trades types, who are useful early on, into specific responsibilities. "When you grow very quickly you force specialization on people who aren't cut out for it," says Eric Giler, president of Brooktrout Technologies (No. 63), a Needham, Mass., company that makes hardware and software for telecoms. The versatile employee who can handle customer complaints and do some accounting may not blossom into a CFO.

The second mistake is taking on people in a rush when the company goes through a growth surge. "My rule of thumb has been that for every five people I hire, one doesn't work out," says Giler, whose company has grown from a handful of people to about 400 over 17 years. "The costs of that in hiring and training and the impact on other employees are huge. It slows you down." To avoid errors Giler has worked at spending more time in the hiring process, interviewing the prospect for a key position six times rather than three, and meeting him in different settings--over dinner with spouses, for example--rather than just across a desk.

3 DON'T ASSUME TREES GROW TO THE SKY

The Chinese proverb wisely observes that this cannot happen, yet some fast-growing companies act as though their revenues will keep soaring at exponential rates forever. Unfortunately, as Scott Harris, CEO of Cleveland-based Crazy Bones, discovered, that's not necessarily so. Harris' company sells a line of marble-sized toy figurines that kids collect ($1.99 for a pack of four). Crazy Bones scooped up $3 million in revenues in its first year, 1999, and Harris' guerrilla marketing strategy, which included taking the toys to schools and parents groups, worked so well that he was written up in the Wall Street Journal and USA Today. Sales leaped to $22 million in 2000, and Crazy Bones hit what seemed like the jackpot: McDonald's decided to hand out 100 million Crazy Bones as a promotional gimmick. No direct profit went to the company, because McDonald's planned to manufacture the toys on its own. But the exposure in thousands of McDonald's restaurants across the country looked to be a sure thing for creating a marketing frenzy. Harris bet the ranch, figuring that his company's sales would double in 2001, and he built up his inventory accordingly.

Instead sales went flat. Why? Six-year-olds are fickle. "You never think your second year is going to end up being your best year, but that's what happened," says Harris. Crazy Bones has since laid off half of its 30 employees and is stuck with a mountain of unsold toys. An entrepreneur has to take risks, but a more realistic bet for Harris might have been that the McDonald's deal would boost sales by, say, 25% rather than 100%. "If I had it to do all over, I would have been happy with what we had," Harris says.

4 DON'T SIGN CLIENTS YOU CAN'T HANDLE

If turning away potential business sounds like a bad idea, consider the recent collapse of Chase Bobko, a Seattle software company that expired this past May. Founded in 1987, Chase Bobko steadily built a successful business on programs that allowed clients to manage huge volumes of information on the Internet.

The Website management business took off in late 1998, and overnight Chase Bobko became the category leader. It signed up new clients at a furious pace, bringing in both Motorola and Boeing in a single week. Revenues ballooned from $2.2 million in 1999 to $5.6 million in 2000. Unfortunately, those new clients were more demanding than the company had anticipated. "We had a great, flexible relationship with Microsoft in which there was an understanding of the technical problems and therefore a lot of tolerance on both sides," says Patricia Chase, one of the firm's three owners. Its newer clients were less technologically sophisticated--especially at the management level she dealt with--and needed more handholding. In some cases the clients' various departments waged internal war over Website priorities. Chase Bobko hired strategists to help clients solve their problems, but it couldn't hire and train the strategists fast enough.

In hindsight, Chase says, the company should have turned down some new business. "At the height there was so much of it that customer service declined. Our people tried to be attentive, but they were overwhelmed." Of course, the dot-com decimation last year didn't help, but with better client relationships, Chase Bobko would have had much better odds of surviving.

5 DON'T OVERSTAY YOUR WELCOME

Any honest CEO knows the odds are vanishingly thin that the same person who had the imagination, guts, and perseverance to start a company can also run it once it becomes much larger. The trick is knowing when to call in a pro. Bob Saracen, senior consultant for Bishop Partners, a New York City executive search firm, says that when he looks for a CEO to replace a company's founder, he first addresses a crucial issue: If a professional CEO is the answer, what is the question? "The founder often has an instinct that he needs someone, but he hasn't really thought out why or what problem he's trying to solve," says Saracen.

Typically the founder wants someone to take care of an immediate external problem, such as raising money--that is, a "first-stage" CEO who will last a couple of years and then be replaced. Experienced VCs generally see through that scheme and recognize, as the founder should, what a stressful upheaval a CEO transition can be.

Worse, even though a founder can go through the motions of searching for a replacement, she might still resist leaving. Maybe she avoids interviews with candidates, or meets several who are highly qualified and rejects them all. The emotional turmoil that leads the founder to such delaying tactics is understandable, but for the company it can be ruinous. The market for CEOs is always tight, and allowing talented prospects to slip away while the founder struggles with her psyche is a dangerously wasted opportunity.

Now that you know the five mistakes to avoid, you can go out and grow with more confidence. And maybe even enjoy it.