I hope the OP is not an experienced punter because you have to learn very very early on to be suspicious of anything that could backfire.
Never pay in advance, never use any traceable means of payment.
Think how you know the picture is genuine, the advertiser is genuine etc etc. Or else realise you stand to lose your money and get nothing in return.
Read a lot of forum discussions on various sites where escorts are discussed and reviews written to become aware of what not to do or at least to realise the risks you are taking and if, as may of us may do from time to time, to take a punt and put anything bad down to experience.