We're previewing the holiday shopping season with a series of articles on how to make the most of Cyber Monday -- online retail's answer to the day after Thanksgiving.

You may say you're "working" during lunch, but we know what you're really up to. The National Retail Federation reports that last year, 61 million people hunkered down in their cubicles and shopped online for holiday gifts at the office.

While you're trying to avoid getting caught (and trying not to drip salad dressing onto your keyboard), identity thieves may be hard at work trying to steal your credit card number for a little furtive shopping of their own. Foil them by using one of these online shopping strategies.

Use a fake ID
Credit cards offer a measure of protection against fraud, making them a great online shopping tool. If there's a fraudulent charge to your card, federal law limits the amount you owe to $50. Many credit card issuers go further, with "zero liability" policies.

Some cards offer an extra measure of Internet security, letting you adopt an alias for online purchases. This means that you can replace your real credit card number with an alternative generated for a single online purchase, or for use with a single retailer.

These fake IDs allow you to shop online without ever revealing your real credit card number, so you don't have to shut down your entire account if the fake number gets into the wrong hands. Some programs also allow you to put spending limits on transactions using these aliases.

Bank of America (NYSE:BAC) calls its program ShopSafe. It's available to customers who have a Bank of America credit card and use the company's online banking service. Citibank (NYSE:C) lets customers who hold certain credit cards generate so-called virtual account numbers for use online. Discover Card (NYSE:DFS) calls their fake IDs "secure online numbers."

Check with your credit card issuer to see whether it has a similar program. If not, and if you're a frequent online shopper, consider whether it's worth the hassle to switch to a card with this cloaking device.

Put on your secret decoder ring
Cards that carry either the Visa or MasterCard (NYSE:MA) logo may be eligible for a security program that both companies offer in similar forms. The security features allow users to set up a special PIN for Internet shopping. Once you've signed up, you'll be prompted to enter the secret code when you purchase items online.

Assuming no one else can get their hands on the code (don't write it on the card or keep it in your wallet!), this can block some unauthorized attempts by hackers who try to shop using your good name and credit. Not all online retailers require the code, which limits its protections. Check with your financial institution to see whether the card you carry qualifies.

Use a go-between
If you're purchasing far and wide on the Internet, you may consider using an electronic payment system that handles all your purchases. It can theoretically reduce your exposure online by reducing the number of retailers that have access to your financial information.

A growing number of merchants allow customers to use an electronic payment system like eBay's (NASDAQ:EBAY) PayPal or Google's (NASDAQ:GOOG) Checkout. You might not be able to use these systems at all your holiday shopping destinations.

Put on your invisibility cloak
Going through all this trouble to hide your identity online won't help if your computer is riddled with viruses sending your private information out to hackers worldwide. Keep your computer safe, and your financial information secret, by installing antivirus and antispyware software. Update it frequently to stay on top of the latest cyberthreats.

To stay safe this holiday season, keep reading and find out:

Will your fingers do the shopping on Cyber Monday? Stick with the Fool to get the best advice on saving money and staying safe.

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Fool contributor Mary Dalrymple will avoid the mall at all costs this year, but she welcomes your virtual feedback. She does not own stock in any company mentioned in this article. eBay is a Stock Advisor recommendation. Discover Financial is an Inside Value pick. Bank of America is an Income Investor selection. The Motley Fool has a cheery disclosure policy.