Another good source of information is the U.S. Secret Service 419 scams page

We do not tolerate abuse of our system or any kind of fraudulent or criminal activity and will immediately bar from our system any user suspected of such. However in common with all other public services of this type we cannot possibly prevent all occurrences.

Your best defence is common sense. If a deal doesn't seem right or something is well below the normal price walk away from it. Here are some suggestions.
• DO pay by credit card if possible. You then have some protection from the credit card company in most cases.
• DO meet the buyer/seller and use cash as payment where possible. You can then see exactly what is being sold and get immediate payment.
• DO use an escrow service such as Auctionpix. Note that some scammers direct you to untrustworthy escrow sites so only used well known and recognised escrow sites.
• DO NOT pay money direct into someones bank account or send them a cheque unless you are prepared to accept the risk that you will never receive whatever you paid for or it doesn't work, is incomplete or is not as described.
• DO NOT assume that receiving money via payment systems such as Nochex, Paypal etc gives you 100% guarantee of payment. It is not unknown for them to confirm payment into your account then a day or two later to retract that saying the payment was fraudulent.
• DO NOT have anything to do with anyone contacting you saying they are from Nigeria, South Africa or any other African or South American country who want you to send them your name, address and bank account details. They also sometimes claim to be from Holland or Canada.
• DO NOT accept a cheque or money order for more than your asking price and send the difference to the 'buyer'.

Many people have been contacted from African, European, or U.S. buyers involving a common scam. Most of these people are actually based in Nigeria, regardless of where they say they are located.

A typical Example:
• Your car, boat, campervan etc. is for sale for £3000.
• The buyer wants to have his friend, business partner, or employee send you £6000 because his friend or business partner owes him £3000.
• You are supposed to cash his cheque for £6000 and then send the remaining £3000 to the buyer, usually by Western Union.
• DO NOT DO THIS! It is a scam. You deposit the cheque and then send the buyer the extra £3000. The bank cheque either bounces or was a forgery and you lose your £3000. They don't want what you are selling, just the cash - the goods are never collected.

A similar scam:
• The buyer sends you the cost of your item and the cost of shipping. Later, they says they have taken care of shipping and ask for you to refund the shipping cost. They keep your refund and the original cheque bounces.

• Beware of anyone "representing a client".
• Beware of any buyers from Nigeria, Saudi Arabia or Egypt who want to wire you money.
• Beware of anyone who does not ask you specific questions about your vehicle.

Why do they say they want to money sent by Western Union? Because this puts cash directly into the scammers hands immediately.

If any deal requires you to send the buyer money, it is a scam.