"Count" Victor Lustig was a con man of considerable note. Born in 1890, by the 1930s he was wanted by approximately 45 law enforcement agencies worldwide. He had 25 known aliases and spoke 5 languages. He cunningly gained $5k from Al Capone. Better still, in 1925, Lustig posed as a government official in Paris, took five businessmen on a tour of the Eiffel Tower, and then "sold" it to one of them as 7300 tonnes of scrap metal; the con went so well, he tried it again soon after.
He also wrote the following list of commandments for aspiring con men.
(Source: Fakes, Frauds & Other Malarkey, via Marc Manus)
1. Be a patient listener (it is this, not fast talking, that gets a con-man his coups).
2. Never look bored.
3. Wait for the other person to reveal any political opinions, then agree with them.
4. Let the other person reveal religious views, then have the same ones.
5. Hint at sex talk, but don’t follow it up unless the other fellow shows a strong interest.
6. Never discuss illness, unless some special concern is shown.
7. Never pry into a person’s personal circumstances (they’ll tell you all eventually).
8. Never boast. Just let your importance be quietly obvious.
9. Never be untidy.
10. Never get drunk.