But no matter how much education or whatever you give them, some people will try, indefinitely, no matter what you do or say. So it'd be a good idea if the system were set up to make it as hard as possible for them to defraud credit card holders in the first place.
Basically from a security perspective, you've got to layer on as many different kinds of protection as possible. Criminals should be prevented from becoming criminals, the system itself should be more secure, consumers should be more educated and aware... etc.
Just go with the flow control, roll with the crunches, and, when you get a prompt, type like hell.