Getting an initial introduction or two is not nearly so difficult as it might seem. Among students whom I have had perform the experiment of asking their relatives and friends to see if any could provide an introduction to a career criminal, fully a third reported that they could get such introductions.... Moreover, once your research interests are publicly known you get volunteer offers of this sort. From students, faculty, and others, I have had more offers of introductions to career criminals — in and out of organised crime — than I could begin to follow up. And that is hardly anything compared to the introductions obtainable via criminal lawyers and crime reporters (to say nothing of law enforcement personnel).
Be that as it may, there are times when you don't have an introduction to a particular scene you want to study, and you must start 'cold'. In such a situation it is easier, usually, to get acquainted first with criminals at their play rather than at their work. Exactly where this is depends on your individual play interests.... I, of course, find it best to start out in the local poolroom. But if you can drink most people under the table, are a convivial bar-room companion, etc., then you should start out in a tavern. If you know horses, start out at a horse parlour. If you know cards, ask around about a good poker game. If you know fighters, start out at the local fight gym.