You're forgetting a few things:
If you're location just recently got hit with the infection. It is best to stay in a secure location as long as possible. When people just turn they have the strength of the zombies in the latest dawn of the dead, after awhile they become more like the original dawn of the dead.
Zombies can survive in cold/heat easily enough. But they will get frozen like anything else even a little faster as they don't produce body heat. They will do very good against heat, of course they still catch fire.
If you live in the city and outbreaks start happening (no matter where) get the hell out of there. Bad place to be. You either want to be out in the country as much as possible, and preferably way up north to where they can freeze (but be prepared as if they can freeze so can you). Islands are good, but zombies can get to them however it will be more difficult for them to get to. And chances are it'll just be luck if they do. (undertow is a bitch).
Don't trust nobody! When coming along new people, take proper precautions. If on the move, bind their hands, and gag them. If you're in a secure location, and have proper rooms quarantine them with a guard on 24hr duty. Wither they look like they've been bit, cut, stratched, it doesn't matter safety first remember everybody lies. Also if anybody has been in contact (attacked) by zombies (follow last step).