10. Protect Yourself Against eBay "Nigerian Scams"
E-mail "Nigerian scams" are among the oldest and well-known on the Internet, in which you're sent an unsolicited e-mail asking for help to transfer millions of dollars out of Nigeria -- but somehow, it's your bank account that gets emptied.

Well, the scam has morphed, and Nigerian scams are now rife on eBay. This time around they're often pointed at sellers of items, not buyers.

Here's how it works. You put an item up to bid. At the end of the auction, the winning bidder gets in touch with you and asks that you ship the item to Nigeria, or somewhere else overseas. Often, there's a strange story attached -- a common one is that the bidder lives in the U.S., but has just adopted a child in Nigeria, and wants the item sent directly to the child there.

The winning bidder sends you what appears to be a PayPal notification, saying that the item has been paid for. Or else he sends you an e-mail saying that as soon as you send him a confirmation that you've shipped the item, he'll pay you via PayPal.

Ship the item, and you've been scammed. The PayPal notification was in fact a forgery, and, of course, if you first ship it before getting payment, you'll never get paid.

How to protect against it? First, never ship an item until you confirm that you've been paid. Don't trust an e-mail from a bidder, or from PayPal itself, that appears to say a payment has been made. Instead, log into your PayPal account and see if there has in fact been a payment.

Second, only sell items to people who have already bought items at other auctions. Scammers often set up new accounts for scams, and these accounts have zero activity. If you see a high bidder on an item of yours with zero activity, go to the Canceling bids placed on your listing page and fill out the form for canceling a bidder.

By the way, some scammers recognize that zero activity may work against them. So some of them look for 99-cent "Buy It Now" items and buy a number of those, building up solid buying activity. So you should also look at the details page of any potential bidder -- if all the items are of the 99-cent Buy It Now variety, there's a good chance he's a scammer.

If you know or suspect that a particular user is a scammer, you can also block him from ever making future bids on anything you sell. Go to the Blocking a bidder/buyer page and fill out the form.