As for making sure that the buyer is genuine, that’s a trickier one and it kind of relies on you using your own radar to check them out as you’re talking to them. But no, never sign over anything or hand over any keys until a proper payment has been made. If you’re really worried you can arrange to meet the buyer at their bank or building society, and have the manager confirm their identity. Generally though, all you need to do is to wait for a cheque or bank draft to fully clear into your account and then you can hand the car over. Don’t accept things like PayPal payments and preferably don’t arrange for direct electronic fund transfers as this involves you handing out your own bank details.