How can you fight off zombies in the zombie apocalypse

Massive head trauma or decapitation. It's been said even a decapitated head can still bite. Watch those ankles.
Get the brains. You're probably better wth a blunt object rather than gun, although when you run out of bullets i guess you could use a rifle or shotgun as a blunt object. Baseball bats, hockey sticks and other heavy sporting equipment would proabaly be your best bet, also dense poles, shovels, wrenches, that sort of thing. And remember canned food, and get up high, it's not in a Zombie's nature to climb up stairs unless they're directly chasing prey.