Interesting topic for me. I can get quite long winded about it. I also have some views that a lot of people might not agree with on this. I will do my best not to offend anyone's sensibilities. Please understand that this is my view point.
Survival Kit - yes, I have one.
Anti-biotics - you can get the pet store ones for fish tanks without a prescription. They do the same thing.
Full pack of batteries. D, C, & Double A. Extra life.
Roll of Quarters
Case of MREs
2 Bottles of Vitamins - I have the chewable, kids ones. They do the same thing.
First Aid kit, complete with adrenaline shot, extra gauze, and tape.
Extra socks, the thermal ones.
King sized, heavy duty garbage bags
Pack of Bic lighters, Lighter Fluid, and a zippo
Steel Toed boots
When it comes to firearms, it depends on the scenario, buuuuut. I have a crappy High Point .9mm. .9mm is the most common pistol ammunition there is. Though my preference is for my sexy .45. Also keep a Mossberg 12 guage and a box of shells, a lever action 30-30 and a box of shells too. My 30-30 has a scope and is sighted in to be dead accurate at 100 yards. My shotgun has been modified with a side saddle, foregrip, and flashlight that I can turn on and off by squeezing the foregrip trigger. The first one is Bird shot. The next four are double odd buck. The last one is a slug, just for good luck.
I've also got a civilian model AK-47 and an AR-15. I have enough ammunition for each, but again, it depends on the particular disaster as to which one is used. Sadly, it will be the AR-15 in most cases. In truth, I'd probably only bother with it if I was forced to hunker down.
You may be wondering why I don't carry water. 2 reasons. It's heavy and cumbersome, and it's easy enough to get and purify if you've got half a brain. You may be wondering why I don't have any blankets or stuff like that. Again, heavy and cumbersome. I'm quite capable of starting a fire if need be, and breaking into a place that I can secure if need be.
Now, I am the sort who makes up for being slow by carrying extra bullets.
Let's assume this is a major disaster and collapse of government on a large scale. (Yay, the South really does win the American Civil War) Let's also, to avoid potential ethnic, religious, and other social conundrums here by sticking to a Zombie Apocalypse. At least for now.
Here are the things you need to remember.
1. Stay mobile. The last thing you want to do is hunker down. Walkers, Runners, crazed cannibal fanatics, whatever the type, you need to stay mobile. If you hunker down, sooner or later you are going to attract attention. Even something as minor as a baby crying or lighting a fire. If you're not attracting zombies, you are attracting other survivors.
2. Zombies are affected by terrain too. Therefore you need to keep to areas where the terrain is to your advantage.
3. You need to be able to survive for about a year. By that point, the zombie's body will decay and deteriorate to the point where decomposition has already killed it for you.
4. Live and let die. Discretion is the better part of valor. If you get stuck with a woman and kids? Leave them behind. If you've got wounded? Leave them behind. If something is a hundred yards away from you? Ignore it and quietly move on. There's no point in wasting ammunition, exposing yourself, or drawing attention.
5. Everyone is an enemy until they prove otherwise. You remain cautious, alert, and aggressive. You show no mercy and no empathy. You're trying to survive, not die.
Now, lets assume it's a natural disaster, and/or we blast ourselves back to the stone age.
Most of the above rules still apply. Though in this type of situation, the barter system becomes available. At which point, you need to also remember
A. Money is worthless.
B. Bullets, Medicine, and Women become currency. Sorry ladies, but it's true. You've got something most men on the planet want. It'll help you get what you want. I'm not trying to be sexist.
C. Cigarettes & Booze are also highly sought after commodities.
D. People are, by their very nature, herd animals. They will eventually re-establish a community and sooner or later one community will produce something the other wants and the cycle will renew itself.
Now, let's assume it's the worst of all possible scenarios, at least for America. WAR.
If it's a Civil War, we're absolutely screwed. However, you'll want to make sure you're stocked up on your bullets for the AR-15. They now are the most common type of ammo. If it's a foreign army invading the United States, they are screwed. There isn't really a chance they can win. There isn't much of a chance at all. Even if the most logical choice, an EMP detonation rocks several major cities, it's still virtually impossible to do it without the rest of the country knowing. It would only be possible to blitzkrieg and disable EVERY major city's source of government. Even still, the civilian population is too prepared to fight. Add to it, that in this sort of event, mobilizing the military for counter offensives across the country is one of the few things the surviving government will actually be on point about. Even the worst case scenario turns out quite a bit like Red Dawn. Hooray for the Tex/Mex border and the Southeast.
Some things to remember here are...
1. Avoid the mountains. Anyone familiar with what happens in the mountains? Soldiers can't hit you with red dots. So red dots turn into red triangles. Mountains become hills. Hills become rubble.
2. Statistically, 1 out of every 3 homes in America has a firearm. 3 out of 5 of them have multiple firearms.
3. The enemy of my enemy is my friend. Kind of. At least until the bullets stop flying at you both.
4. Celebrities, politicians, and religious zealots are the first to die. Following them will be the peace keepers, those who are too vocal and paint targets of themselves, sympathizers, and the extremely wealthy. They have nothing of actual value. And, as nature intended, survival is for the fittest. Might does in fact, make right. You can't talk a bullet into not killing you. And someone who is trying to kill you wants you to be dumb enough to stand up and try and talk them out of their mission. Modern media likes to glorify the "art" of diplomacy and tell a story with a happy ending. The truth is, you get killed, and if you're even remembered, you'll be mocked. You won't be a martyr, a hero, or anything of the sort. You'll be just another dead body. Kinda gloomy, isn't it?
5. Avoid any source of major transit. That's one of the easiest ways to get yourself caught and ambushed.
6. The Bayou is your friend. Everything there is edible, even if it wants to eat you too. Heavy armor units can't penetrate it, and the naturally dense cover protects you from being spotted. The natural heat means you have to worry less about shelter. And heaven forbids you get a boat... then you head on out to one of the many places in the Caribbean. Congratulations, you're destined for survival, provided you don't screw it up on your own at this point.
I digress. I've already said too much, I think. But I can go on and on and on about this topic. I also hope nobody is offended by anything I said. It is not my intention. :)