*This part is for newbies. Skip down to the dashes if you already know this stuff.*
Okay, so first of all, a zombie is a reanimated corpse that lurches around looking for human flesh. Different breeds may be reasoned with, or even "cured" back to the original personality. However, the most typical zombies:
-Are incoherent. They will not be reasoned with or threatened.
-They don't sleep.
-They seem to like brains, but most will settle for a nice hunk of your flesh.
-The come in different speeds, from crawling to shambling to running. Most are shambling along at a slow slow walk.
-They do not drown or asphyxiate.
-Some will burn easily while others will not burn at all.
-Most zombies will "die" from severe damage to the head.
-It is said they are attracted by sound, but this varies.
-VERY IMPORTANT: The most dangerous thing about zombies is that if they bite you and you die before your brain is destroyed, you will come back to life as ANOTHER ZOMBIE. That's how they spread their numbers generally.
A person that becomes a zombie loses all of their personality.
During zombie apocalypses:
-There is no electricity.
-There is no running water.
-There is little to none widespread communication.
-The government is thought to have collapsed.
-Few people are surviving, most have become zombies.
-It begins somewhere, but quickly spreads worldwide (there will be no foreign help).
So you're preparing for going out into a zombie invasion. Remember to pack the following:
-Heavy duty gloves, shoes, and PANTS (no idea how many people got infected from a bad bite to the shins).
-Canned food or other non-perishables. Best if high energy and low weight.
-Water. Drink sparingly, refill at every good opportunity.
-Waterproof jacket or poncho.
-Helmet, if you have one that doesn't obscure sounds and sight.
-Weapons (we'll get to that).
-Change of clothing (just one, clothes should be thick, comfortable, and long lasting).
Long Lasting Survival (1)
Okay, so assuming that you're a person living in a developed area in a zombie apocalypse situation, you will need to find the following:
-Other uninfected human beings.
In a developed area, all resources come from rural areas. Most foods were never meant to replace themselves, so it is extra important to get to a food source. The best place to find resources is in a mall. Personally, the ideal situation is to have a nice flat area around a Lowe's + Walmart. If you know of such a place nearby, aim for that immediately. Drive fast but carefully, just know that it's gonna get a lot worse before it gets better.
Once (if) you get to the place, block all entrances with the strongest material possible. In Walmart you use carts and shelving to create a temporary barrier. Lowe's usually sells wood or brick or stone or cement powder, the construction is fairly simple.
Remember to keep a few doors open, like steel doors with safe locks and loading bay doors with a clear lookout.
If the electricity is gone, dry out all the meat products to make them last longer or marinate them to use up the various sauces lying around. Save the bottles, they will be useful later.
Set up a water collection system on the roof with large tarps/cones connected to large trash cans. They should come with a cover so that the water stays fresh longer. Bottle waters and canned foods and other non-perishables are to be collected and rationed out for maximum usage.
Most likely this place will not be self sufficient, so you need to be very careful about food.
Long Lasting Survival (2)
If you are in a non-urban area, the approach is going to be different.
Non-urban means really small towns (mainly farmland) which means very little population. The best case scenario is to have, again, large open space with lots and lots of guns.
The upside to having a rural area means the bulk of the zombie army is going to have to come from a city. You might be able to clear out all the zombies in an area and gather up all the survivors in a week, months before a major invasion.
Take advantage of this right away. Secure any gun shops, markets, farms, and hardware store in a given radius or collect them all to be stored at the main base. Set up a large parameter around farm land, enough land to ensure food for several years. Use wires, large tree falls, or fences with a layer of spears in front; you want a large, reliable barricade that's easily defensible.
Before doing all this work, find a water source. Rivers and creeks should not be trusted unless they come from a stream because there will be a gap to let the water through and zombies will attack that gap. Rivers can also be polluted from upstream, making them unreliable. The best source would be a well or a large pond. Boil the water that comes from natural sources. Arrange water collection devices on barn roofs and such.
Meat should come from farm animals. You might have to resort to eating horses or dogs. Fish is good because it can be dried with out too much fuss, but do not over fish in a small pond!
Constantly build. Forage everyday but be prepared for an attack at any moment. Stockpile resources from surrounding lands. Time is your friend, use him/her well.
It is important to be self sufficient!
Worst Case Scenario
Anytime you cannot get to one of the above scenarios, you are most likely going to die.
Some things to watch out for:
These guys. They will blotch any job that you pull, stupidly charge into a mob of zombies, and open the door to the outside while looking the other direction.
Identify them IMMEDIATELY. Do not allow them any guns or responsibility, but make them feel important. Find some use for them later.
They will hurt others, take advantage of the situation (rape most of the time), and generally work for themselves rather than the group effort. Let them make a small mistake to show their character, then blow their head off (or permanently incapacitate them). I'm not kidding, DO NOT let them get any sort of power whatsoever, they will endanger or kill off the entire team for their own sake.
Lack of Weaponry
Be very careful of this. Especially ammo. Take careful shots with your legs and shoulders braced against the recoil for max effectiveness while shooting. Make EVERY SHOT COUNT. If you have a shotgun, try not to use it if you have another gun. Shotguns' wide range is very useful against zombies so save it for emergencies.
If you have no guns, you may be good with another weapon with range. Spears, staffs, baseball bats, crowbars, farm tools like pitchforks are all very good. If it's not sturdy enough to hit things with, sharpen an end and use it to stab zombies in the face.
The longer and stronger it is (no innuendo intended) the better. Attach a bayonet to rifles or shotguns if it doesn't get in the way of the sight or muzzle.
DO NOT HESITATE.
Psychologically, this is all very disturbing. The zombie coming at you might have been someone you knew. SHOOT/STAB/BASH their head anyways, the person is gone, the zombie you see in front of you is mocking their living image. Get rid of it to ease your friend's soul. Convince yourself they are not curable and they have no memories of you. Just kill it.
*In a situation where a living person's been bitten and they are going to die before becoming a zombie: tell the afflicted that there is no more hope. Amputations on limbs can be tried, but most likely will not work. They have to choose between going peacefully or going violently.
If they want to go peacefully, lock/tie them up securely, wait for them to turn into a zombie, then shoot the zombie. If they wish so, you can kill them right away. DO NOT HESITATE. One second is all it takes for a zombie to bite you in the neck.
If they want to go violently (with a fight, they're not willing to give up), immediately disarm them or do a preemptive strike. Do not drag it out or have other people get injured.
Most of all, avoid feeling guilty. For anything. This is survival, not a bloody soap opera. Try to keep as many health young people alive as possible, in hopes of starting a new civilization. Which leads us to our last section.
After the Survival
If you're sure you can stay in one place safely for at least a few months, it's time to get to work.
For scenario (1):
The one thing that we have more than zombies is intelligence. We have the brains, they have endurance and numbers. What we need to do tactically is to make them lose the most numbers for the lowest cost.
You can do this with traps. Chemical fertilizer and vegetable oil mixed together makes a pretty good explosive with another detonator. Put these in small bottles attached to a fuse and some gunpowder. Test it out, then load it on the outside with ball bearings. They will become hand grenades, for the price of maybe have a bullet's worth of gunpowder and some ingredients we'd never use otherwise.
The best trap would be to have a big deep pit laced with these and long stakes. The zombies fall in and can't get back out. Wait for them to pile up, then detonate. You can repeat this with sharpened iron stakes and fire.
Make ammo from readily available materials like bamboo, decorative stones, or even concrete balls. Launching these with industrial rubber bands can cause some major damage for little cost. You could even make a game out of it (who can peg the most?).
If you can keep the zombies at bay for long enough to get some cars. Armor them, load up with food, and move on to the next location. The supermarket's food won't last forever, and it's important to realize when a good thing's come to an end.
For scenario (2):
Just endure. It's as simple as that. With a farming community, your main goal is to raise another generation while being self sufficient. If scenario one's goal is to hit hard and move fast, your goal will be to sit still and defend.
Always keep a lookout on the horizon. Continually stockpile resources. Recruit more people or get some kids born.
Eventually, if you can grow large enough, you can set out a party to establish an off shoot farm right outside the old one. Set up exactly as before and continue to expand until you have a regular community going on.
This scenario has the highest probability for lasting out the zombie apocalypse.