Attractive - In the real world, being attractive is good, but in a horror film it is a no go. Masked killers and sick pychopaths love nothing more than to hack away at a well-proportioned pair of titties or a perfectly-sculpted booty. So if you find yourself and your friends being stalked by a guy in a hockey mask holding a machete, you need to ensure that you are as plain and unnattractive as can be. Plaid shirts and wellington boots could be your only hope of survival.
Arson - When all other attempts to kill the bad guy or monster have failed, resort to fire. It is a well known fact that 99% of supernatural slashers are vulnerable to flames, and one acceptable plan for survival would be to trap the bad guy inside a building and set light to it. This will ensure that you reach the end of the film alive whilst ambiguously leaving open the possibility that the killer survived to make the sequel. Fire can also work against nightmare-invading child-killers - especially if you find and burn their remains in the real world.
America - Nearly all horror movies take place in the USA, so if you live there, MOVE!
Acid - Acid is affective against all types of killers (even toon-killing maniacs. See Roger Rabbit). It is hard to procure, but there is a moment in every horror movie where one will find themselves in the empty corridors of a high school. It is this time when you should quickly seek out the building's science lab and look for any beakers of smoking, clear liquid marked with a skull and crossbones. Said liquid should then be applied to killer's face ad nauseum...
Side note: the narcotic 'Acid' is not a survival tool and will in fact lead to an immenent death (see later entry DRUGS).
Attic - The attic is useful for several reasons during a horror film. It is a place to hide while the killer stalks the floors below (you should usually be able to find a small hole in the floor to watch at your leisure). When eventually discovered, the attic will allow you to partake in an exciting rooftop chase that starts from an awkwardly shaped window and ends with someone falling to their death (hopefully the killer).
The attic is also useful because you will enevitably find an old dusty chest that contains back story on the killer and potentialy objects to destroy them. This chest will also allow you to discover that your Gran knew all about 'everything' from the start but didn't tell you about it because they were blocking it out in an alcohol-fueled, decades-long bout of denial.
Accidents - Never step backwards into a road whilst arguing with your friends. A bus WILL hit you!
Adults - Adults are absolutely unwilling to believe anything you say concerning masked killers or your impending death, despite the fact that they know all about it really. In fact in many cases the killer is stalking you because of something your parents did, which makes it even more annoying that they won't listen. Do not worry though, because there is a good chance that they will drink themselves stupid in the second half of the film then later meet their deaths in some mad attempt at redemption.
Alleyways - AVOID!
Alaska - Any place that always snows will be plagued by some sort of Vampire. Move immediately if you live in one of these places.
Ally-Oop - This is a maneuvre in basketball where one player throws the ball in the air whilst their team mate catches it and 'dunks' it in one motion. It will not help you in a horror movie.
Alligators - When flushed down the toilet as unwanted pets, they will roam the sewers reaching unbelievable sizes. If you find yourself underground, encountering an alligator is almost as bad as all the poo.
Animals - You will find most animals in horror films are rabid and dangerous. Except dogs - dogs are heroes. If you want to survive, you may need a dog. You should name him 'Chips'.
Apes - Apes and Monkeys carry zombie diseases. AVOID!
Asimov - If confronted by killer robots, consult the rules of Asimov.
Assistant - If you are an Assistant and you sleep with your boss, YOU WILL DIE. Usually in a way involving office staionary or some sort of xerox machine.
Asshole - If you are an asshole, it is your obligation to start out by giving everyone else shit, but slowly throughout the course of the film you will become a badass anti-hero that others rely on. You come to realise that your poor childhood is not your fault and that the only way you can change things is by changing yourself. If you are an asshole, you may just live.
Astronaut - Never trust an astronaut. They are not the same as before they went to the moon, becoming somehow different and strange. The patches of scaly skin on their neck is also very unsettling. If you are female they will want to breed with you as soon as possible...
Australians - Australians attract sicko 'outback killers' and giant crocodiles. They are also always 'attractive' (see Attractive). They also carry backpacks which are constantly snagging on things, causing you to stop, turn back, and free them. They are also dangerous at sea as they are the natural diet of sharks. Do not make friends with Australians, they will get you killed.
Axe - An effective weapon against slasher-killers and bug-like alien infestations. The axe is easy to find and makes you look really cool. It can also be used for opening doors and cutting off infected limbs.