AFTER RONNIE FLISS lost her job as vice president of data intelligence for New York-based financial-services giant CIT Group (CIT) in 2002, finding another job seemed almost impossible. Not only was she 51 years old, but she was also a woman in middle management. “It was a triple whammy,” she says.

After six months of frustrating (and fruitless) job searching, Fliss decided to take matters into her own hands. Inspired by her beloved basset hound Murray, she steered a sizable chunk of her severance pay into launching Fat Murray’s Doggy Treats. Now the six-year-old Montville, N.J.-based venture is a thriving purveyor of all-natural dog treats.

During tough economic times, when companies are laying off workers en masse, some former employees discover that they're no longer desirable in the workplace — whether it be due to a lack of available jobs, their age or the amount of salary they’d require. In such cases, some find that the only option left is to go into business for themselves.

Of course, starting up a new business venture is risky no matter what the economic climate. And these days, times are especially tough, even for the most capable would-be entrepreneurs. Amid a global stock sell-off, many banks are tightening credit standards — making it harder for businesses to raise capital. On top of that, prices for fuel and materials have surged.

But if you have a strong career track record and a tidy nest egg, your chances of start-up success improve dramatically. Here are four key ingredients that former employees can use to become successful entrepreneurs:

Seek a Recession-Proof Business

Choose a business that will excel no matter what the economic climate, says Karin Abarbanel, author of “Birthing the Elephant,”, a guide to launching businesses. Find out which industries are actually growing right now such as technology, energy and health care (for more industries, click here. Also, target customers who are actively buying. Historically, when the economy slows, the government boosts its spending. Setting up a business that’s in a position to land government contracts would help you take advantage of that trend.

Another option to pursue: opening a franchise, such as the wildly successful frozen yogurt chain Pinkberry, or burrito powerhouse, Chipotle Mexican Grill (CMG). Such business ventures still entail risk, but can also provide access to tried and tested business concepts, says Jon Schallert, a small business consultant in Longmont, Colo. Some franchises even offer loans, so prospective business owners aren’t beholden to banks for financing.

Build Up a Sizable Nest Egg

Of course, starting a business requires money. Typically, entrepreneurs rely on a patchwork of friends and family, as well as angel or venture investors. Unfortunately, much of the investment power is dried up. Tapping other sources of income is a necessity. Employees who’ve been laid off, for example, may dip into their severance pay, notes Abarbanel.

According to Kate Wendleton, president of the Five O'Clock Club, a New York career coaching organization, the average severance package usually amounts to one week’s pay for every year of employment. So, a laid-off employee who earned $2,000 a week, or a little more than $100,000 a year, and worked at a firm for 15 years will probably walk away with about $30,000 in severance.

While a severance package may serve as a ready source for start-up capital, small business consultants warn would-be entrepreneurs from spending too much of it — especially if they don’t have other savings to rely on. To be on the safe side, make sure you have at least two years’ worth of salary or a third of what the venture costs saved up before pouring your severance into it, says Schallert. If you don’t have the cash, then make sure you have equity in a home or other investments that's equal to that savings.

Parlay Your Experience

Prior work experience is critical for starting a new business. Rob Fairlie, a professor of economics at the University of California at Santa Cruz, who has studied entrepreneurial success factors, says those starting up businesses similar to their former jobs perform 10% to 40% better than those who start firms that bear no resemblance.

Experience also aids financing efforts, says Ed Harycki, chief executive of Swift Financial, an online commercial financing firm in Wilmington, Del. In light of the on-going credit crisis, banks and other lenders aren’t just relying on mathematical models such as credit scores anymore, he says. Many financial institutions are employing “judgmental lending” practices that weigh a borrower’s entire package from business concept and execution plans to future goals. Now, he says, “the more relative experience the entrepreneur has, the better the chance of getting a loan.”

Network

Maria C. Coyne, who focuses on small-business issues as executive vice president of KeyBank in Cleveland, notes that people with years of career experience should exploit their well-established networks of contacts, customers and clients. By letting these contacts know what you’re up to, they may offer a helping hand or invaluable customers or clients.

“You are a vetted person,” says Abarbanel. “Maybe you can go to a former vendor and get a line of credit.” You may also know some marketing professionals who are willing to pitch in. “It’s about taking the resources that you already have in your existing job and reconfiguring them for your business,” she says.

Other recent Starting Up columns:

• Starting Up: Biz Owners See Red Over Bailout
• Starting Up: Pricing Your Products

("Starting Up," a weekly column written by Diana Ransom for smSmallBiz.com, follows entrepreneurs through the early stages of launching a business. Write to her at dransom@smartmoney.com.)