Become a good shot. Let's be honest, knowing how to work a gun is gonna keep you from either dying or being voted off the island. So get over your hippie all-the-world-needs-is-love mantra and load 'er up. And while you're at it, buy a couple (if you haven't already).
Regardless of who or what you'll be facing, this is probably a good idea. Zombies will attack you, starving or distrusting humans will attack you, robots will do whatever they please with you, aliens will probe you, and the Kardashians just need to be kept far, far away. Whatever or whoever your enemy, shooting them will probably increase your chances of not being attacked, eaten, being made a robot playtoy, probed, or questioning your will to live.
Unless the apocalypse is due to some bacteria that's floating around in the air. Can't really shoot that, huh? In that case, get a gas mask. Actually, get both. The people/zombies/Kardashians will probably still see you as an enemy.