When you buy a prepaid card, you load it with the cash amount you want; as you buy stuff, the goods' purchase total is deducted from the balance. Visa's zero-liability policy applies to prepaid cards, as well. Just remember that these cards are often loaded with sneaky fees. A , for instance, has a $10 "non-refundable activation fee" and a $5 "load fee."

Secure cards: For additional protection online, consider services such as and . Both require you to enter a password to complete a transaction at participating merchants' sites. The lists of participating vendors are short for both services, but if you regularly buy, say, plane tickets on British Airways, using an extra layer of security could help throw potential fraudsters off your tracks.

One last important rule of thumb: Never use wire transfers. "It's just like sending cash--once it's gone, it's gone. You can't get it back," the FTC's Consumer Alert site warns. The agency also points out that using cash equivalents, including debit cards, personal checks, cashier's checks, or money orders, to buy online is wise only if you're familiar with the seller. Buying a $50 herbal supplement from a dubious Siberian pharmacy? Say nyet to cash.

Using any of these methods can help you significantly reduce the chances of being duped by a malicious seller or site hacker. Of course, even if you take steps to disguise your financial information, you should regularly check your accounts to spot fraud more quickly. But with a little vigilance and extra effort, you can stay one step ahead of cybercriminals without losing the convenience of in your pajamas.