Ask for credentials. There's no government entity regulating the time share industry, but most of the major players such as Marriot, Hyatt and Hilton are members of the ARDA and must follow the organization's code of ethics. If members break this code, they lose their membership, Nusbaum says.

When the salesman is done answering your questions, ask yourself some, Schreier says.

"Do you understand the product? Do you like the product? If you had the time share, would you, in all likelihood, use it? Is the money for the time share going to be spent anyway?"

6. Pick a vacation spot because you like it. This may sound like a "duh" suggestion, but many companies offer several destination choices. And when it's time to choose the vacation, people "realize they don't like a single location," Schreier says. "You shouldn't be buying a time share if you don't plan on using it."

Whitlock agrees.

"You're restricted to go to the properties owned by the time share company," Whitlock says. "If your plans change ... and you cannot make it, you lose your weeks allocated to you."

Knowing exactly where you want to go works to your advantage.

"Let's say I want to go to Puerto Vallarta, Mexico, every year for Christmas week," Nusbaum says. "Well, I'm very smart to buy a fixed-week, fixed-unit time share at Puerto Vallarta for Christmas week. I'm going to get exactly what I want."

7. Become the second owner. As with any used product, time shares depreciate over time and a perfectly good property worth $20,000 10 years ago could be purchased for $6,000 today, says Nusbaum.

It's a buyer's market, says Whitlock. "A lot of people are looking to sell."

Experts say to buy resales in high-demand areas such as Miami, coastal California and Orlando, Fla. According to the ARDA, there are many reputable Web sites that have listings of the secondary market. 

But buyers beware. Some of these used time shares don't come with the brand-name perks "such as the ability to use the time share at the brand hotels and/or earn loyalty points," Schreier says.  

Sometimes, the new owner gets stuck with the old owner's debt.

"In some cases, good deals turn out to be not so good deals when the original owner hasn't paid the fees and/or taxes on the property in years," Schreier says.

The FTC recommends using local real estate agents and looking the reseller up with the Better Business Bureau. But even practicing due diligence may not prevent you from being misled, Whitlock says.

"When it comes to time shares, it's so easy to be defrauded," Whitlock says. "You don't really know if you got a legitimate deal or not ... because time shares are not regulated and because the contracts are 30 pages long and they're in a two-point type that nobody can read."

Before you go shopping for a time share, it can help to know the terms salesmen use. See "A glossary of time share terms" for more information.