Town - It's pretty obvious what to do as far as town goes. Cop get your guilties; Doc on cop; GS beware of a janned cop/ giving mafia guns.
Mafia - Fake whatever role you jan the best that you can, ESPECIALLY if cop. Vent, try to out the doc and screw with town by disguising your voice as someone else, just don't vent too much, or you'll get caught!