Always check ID!
If you're going to use this type of service, always demand to see an ID, verify it, and then pocket it until after the assignation is completed. Better yet, take a picture of it and keep it: you never can tell if it is a fake, and the "victim" is a plant by the Moral Minority to trap just this type of "evil prevert". A photo of the ID and the "victim" together is going to be pretty good evidence of a setup.
He/she won't go for the picture thing? Walk away, quickly...
Oh, also, make hard copies of the profile and any chat sessions, as anything you say or type can and will be used against you...