I am in the middle of writing a short story set in near-future NYC, and my main characters are helping out a friend who got on the wrong side of a loan shark. I know nothing about loan sharks other than what I've seen in clichéd movies and TV shows, and the Wiki page (http://en.wikipedia.org/wiki/Loan_shark). I want this to come across as realistic, and not trite, but I know nothing about what clichés are deserved, and which are just hollywood exaggerations, etc.
In this kind of a situation, I am out of the "write what you know" league, and firmly adrift in the sea of "do your research". But my question is, other than tracking down a loan shark and shadowing him for a week, how can I find out some of the realities of behavior of the seedier side of this type?
Wiki has a nice little page about the history of loan sharking, and it helps clarify a few of the stereotypes, but I'm interested in a little bit more detail.
Any suggestions are greatly appreciated. (I posted this to sfandfwriters, and got redirected here.)