It is important to remember that eBay is a lot like a marketplace. There will always be a dodgy guy in the corner, selling things that most people wouldn't touch. The trouble is that, on the Internet, these people can be a little harder to spot. Here are Seven tips to help you keep an eye out for the rip-off merchants.

* If it seems too good to be true, it probably is. This holds for everything in life, but especially for eBay. Things that seem too cheap are usually too cheap for a reason – it might be a complete scam, or the items might just be of extremely poor quality. Investigate before you go further.

* Know the value of what you want to buy: There are people on eBay who regularly bid such high prices for used cameras that they might as well have gone out and bought them brand new. Check around for prices first.

* Only bid on real things. eBay has plenty of people who are trying to sell all sorts of schemes and scams. It is never worth bidding for these, no matter how cheap they might be.

* Be careful where you send payment: People may hack into others' accounts, and ask you to send payment to addresses that eBay has not confirmed as belonging to that account – you might send your money and receive nothing in return.

* Look out for sellers who suddenly change what they sell: Sellers can look like they've made lots of transactions, when really they've never sold anything of worth. If they suddenly start selling 1,000 televisions, steer clear – the chances are they're planning to run off with the money.