I did a bit of door work in London when I was working as a security guard up there, I thought it was pretty much the same thing but at nights and more money, got my license, went in the deep end, scared the shit out of me the first few times. Got used to it, was pretty good at talking my way out of things and I can look after myself plus I worked with good staff.
You learn very quickly and you gotta be on the ball.
Gave it all up when a junkie pulled a needle on me, no money is worth getting stuck with that.

Cheers, Mike