Landing a major contract can be the boost a business needs to grow--or it can be the kiss of death. I remember how ecstatic I was to get a lucrative contract, and I allowed the client to monopolize most of my time. Meanwhile, the extra cash quickly turned into extra spending as I anticipated the year-long contract and the monthly retainer that went with it.

Then the client pulled out of the contract. I had failed to read the fine print on the contract the client insisted we use. I didn't realize the company had the right to stop using my services--and stop paying me--until the contract ran out. When I no longer had that client to coddle, I realized I had been neglecting my other clients. I changed my focus to strengthening my relationship with existing clients while putting the word out that I was looking for new ones.

Ashley M. Hunter, 29, president of HM Risk Group, based in Austin, Texas, says she has never had a client as big as the one she landed when she first started her business. She says big clients are too demanding.

"I basically catered to their every need so much so that I didn't really develop business with their clients or with other developers in the industry," she says. "After I spent a year kissing their butts, the owner decided that he wanted to go in another direction when a very large project was just about to hit, and it would have made my year in commission."

Hunter found out that she lost the account to a male broker because the client thought a woman couldn't handle the work. In the end, the other broker didn't work out and the client tried to return to Hunter. Hunter decided not to welcome the client back.

"I fell into a trap of being naive about people's loyalty toward one specific company," Hunter says. She also realized that spending more time catering to her client's needs than tending to her company was bad for business.

Lisa Caplan, 52, founder and president of Touchwood Creative in St. Louis, didn't set out to rely on a single client for the bulk of her video and multimedia company's revenue. But over time, that's what happened. When the market was up in the '90s, her company grew, largely because of that major client.

"As the nation's economy began to suffer in the last year, and our big client examined its own short-term difficulties, it became apparent that we were headed for some tough times," Caplan says. But when that client decamped in 2008, Caplan still had other resources. Planning ahead, she and her team had already begun expanding their operation by adding internet marketing to their mix of services.

"This division has grown considerably and has enabled us to not only survive that tough economic blow from our largest client but to actually sew the seeds for future prosperity," Caplan says.

Having an emergency fund in place can help offset the loss of a major client, says Heather Villa of IAC Professionals, a provider of virtual accounting and administrative services.

"The usual rule is to have at least three to six months worth of savings that cover all your monthly expenses in a money market fund," Villa advises.

But what if you find yourself taking care of your biggest client at the expense of other clients or your company's growth?

"Don't do it," Hunter says. "Keep that client happy and show them the attention that they would not otherwise receive from a larger business, but maintain your business strategy and continue to develop business outside of that large client."

Caplan admits she learned a painful lesson when she lost her biggest client.

"A smart entrepreneur understands that the market can change surprisingly, even if she may not foretell exactly why," Caplan says. "Working to keep your business diversified, lean and smart will pay dividends far into the future."

In my case, I scrambled for six months to patch together a handful of new jobs to make up for the income I lost when my largest client left. Along the way, I worked harder for my longstanding clients, honed in on a new specialty--social media--and brought on a new business partner with business development skills. So far, a clearer strategy for business growth and diversification is paying off. That means distributing those proverbial eggs into several baskets instead of just one.