Muggings something which just comes naturally in my opinion, the only hard bit about it is just daring to get ur ass outta your bunker and do something. its easier if its a 2v1 and theyre distracted, if they dont know where u are, let ur man keep them pinned or draw his fire, then stroll up on his blind side, dont put 15 balls into the back of his head though, not unless u want a well deserved smack at least.
Running and shootings a lot harder, and a skill which u use when mugging some1, best drills for it we've found are running and shooting a stationary point, try at different speeds and shooting from different positions etc. When you have that dialled, try shooting moving targets whilst moving, ie jousting, 1 player on each tape, opposite ends of the field, run the length at the same time whilst trying to gun the other down, same movements used for bunkering, but at a longer range making it harder.
Just ideas, im by no means a pro
hehe