Something I haven't seen addressed before, is how to turn out as one of the good guys. I'd think the best starting point for this conversation should be a few photos (with a bias towards NJ, since it was between those two hotbeds of crime, Philadelphia and New York City).
The entire Teaneck NJ police force, circa 1930.
..and some better detail of your standard wool-coated beat cops and civilian-clothed Supervisors, from the Fairlawn NJ PD.
http://www.fairlawnpd.com/history/im...late_1930s.jpg
It's a big pic, but image trying to find your sidearm, let alone draw it fast during the winter!
FLPD History
...and Camden motorcycle cops in 1928
http://www.dvrbs.com/Camden/CamdenNJ...esInCamden.htm
..and Schwarzkopf's NJ State Police
New Jersey State Police - History -1930's
1928: The first troopers