You think of con men as smooth talkers but just as the psychological research recommends, they bond with others by listening.

Dress nicely, reference mutual friends and similarity, and convey social proof markers like affiliations with impressive institutions.

Social proof is one of Cialdini’s six fundamental principles of influence. Don’t ignore it.

Success in negotiation is strongly correlated with time spent preparing.

The rest of Eric Barker's article is an excellent read:

http://www.bakadesuyo.com/2013/11/scams-and-cons/

Listening is "paying attention", which is an interesting conceit in that it explicitly ascribes a cost to the act.  What con men have figured out is that such explicit costs, when well employed, can produce an outsized payday from a mark.

The con man never stops paying attention to what is, as it is.  The mark never starts...

So I would add confirmation that preparation is important, but that all the preparation in the world won't assure success if one can't recognize what is, as it is, and then improvise accordingly.