I think backpack has to be a given. Gotta carry all that looted useful crap yo!
I reckon firearms are a drawback really. They make a lot of noise and will get you into real trouble in the city (draw attention from the evil brain eating masses!).
Run to the countryside. Lower the population then the less risk I think. That kinda sucks here in the UK cos everything is so close. I suppose it's also only a matter of time before powerstations and nuclear reactors go offline..