Note: I caught on to the scam before it happened on some of these.
1. Customer sends you a money order. You deposit it in your bank. The money shows up in your account the next day. You send the goods and 1 week later the bank removes the credit from your bank and you end up losing the money and your item. A variation of this scam is when they overpay you. So if you sell an item for $100, they send $150, apologize by email and tell you to send the item and refund $50 via check payment. Always wait 7-8 days before shipping out orders via money order payment especially if its a big ticket item.
2. Another scam is when telemarketers call you and tell you that they will work for free. They only make money if your item sells. The trick here is that they ask you to pay for a $400+ list. (List of people they will call). If you can afford it, they will work out a deal with you. Then you are asked to pay by check and submit a document saying that you authorize that company to take money out of your account. After the money is sent, you will never hear back from them again. They also post a phone number but they won't pick up the phone. If you bug them long enough they say they are missing part of your payment and that they haven't begun because you haven't finished paying. Then if you send money again, they will back stop answering your emails and will not pick up the phone.
3. A big scam in play by a company who has F ratings all over the internet is done by suckering you into a life insurance sales job, having you sell your insurance to all of your family and friends (crap insurance), then firing you for not being a "good fit" in the company. Meanwhile, all of your family and friends hate you for selling them horrible insurance.
4. A well known scam is the stolen credit card scam. New marketers get a few nice orders without checking to see if the order is legit. Every merchant account is different but here are a few tips to make sure you are dealing with a legit customer:
A. Make sure the verification system pull up an address and security code match.
B. Make sure the billing address and shipping address match.
If those 2 things match, then you are dealing with a legitimate customer.
5. Anyone asking for a money wire payment through Western Union or any other wiring means is probably trying to scam you. You can accept payment legitimately through those sources but I highly recommend against sending payment.