Exactly what it says on the tin. Here's what I've learned from YA dystopian, apocalyptic and post-apocalyptic novels (mostly quite general, but there are a couple of specific books noted next to the lesson or example they inspired.)
1. The whole "safety in numbers" thing is a myth. If you're going to follow the YA Survival Guide, it would seem it's very, very unwise to hang around with more than a couple of other people. You'll start fighting for control (This is Not a Test by Courtney Summers), at least one of you is bound to be a lunatic, and - the clincher - it's so much easier to hide and go unnoticed when there are only a couple of you (The Outside by Laura Bickle)
2. But that's not to say all of you will survive anyway. Nope. Always remember that: even if there are only two or three of you, one of you is bound to be eaten/shot/killed in some other dramatic way (The Outside). So make sure it isn't you. Betray everyone around you if you have to and shoot innocent people if they're in your way. (Mockingjay by Suzanne Collins)
3. Go shopping. (Life as We Knew It by Susan Pfeffer) The instant you get a whiff that something's up, be it from the news or because the moon's changed position or because you saw your formerly dead neighbour get up and start munching on a squirrel, go stock up on everything non-perishable. Tins, cans, bottles, you name it. Don't forget tons of bottled water and batteries for flashlights. Water and electric supplies inevitably go on the fritz when the apocalypse arrives. It's probably a good idea to keep a few weapons handy too. Apparently the apocalypse turns previously nice human beings into thieving, murdering scum and you're going to want to defend yourself.
4. Barricade yourself somewhere safe(ish). Supermarket, house with an awesome security system, wherever. Find a spot, take all the supplies you can possibly find with you, and lock yourself in. Waiting out the apocalypse seems to result in a lot less drama and a lot more survival than wandering the streets.
5. And once you've done that, don't let strangers in. I know, I know. Do you want to turn into that person? The horrible one in all the stories that doesn't let the intrepid and bleeding hero/heroine in? Probably not. But do you want to be the one who sweetly and trustingly lets the bleeding stranger in, only to then be killed and robbed? There is no such thing as an unpunished good deed in post-apocalyptic YA.
There you go: how to survive the apocalypse, with or without your conscience intact.