So you want to make a horror movie eh? A lot can go wrong there, horror is probably one of the most under-appreciated genres out there and its about time someone made another critically acclaimed horror film and that's why I'm here. I am here help you make the next Alien, the Exorcist, Sinister, It Follows, or the Babadook. So let's get started shall we?
GHOST AND DEMONS, ALWAYS GHOST AND DEMONS
Every horror movie needs a good movie monster, and by monster it needs to be a paranormal entity because forget about sci-fi creatures, that's why no one respects the Alien franchise. Its all about that paranormal, you need that paranormal money, look at great films like Paranormal Activity that have demons and ghost populating the films.
Nearly every horror movie nowadays is on board that paranormal antagonist train. Don't take my word for it, look at the Poltergeist remake nothing but stellar reviews. Aliens, and physical creatures are so boring and uninteresting we've seen it a million times but ghost and demons, that's something new everyone's scared of.
MAKE THE PEOPLE JUMP
Everyone knows the only way to terrify the people is to have random loud noises going off every four seconds to scare the hell out of them, I'm talking of course about the jump scare. There's an art form in making the jump scare, first of all things need to get really quiet for a few seconds and then you need to assault their ears with a loud noise and maybe a scary image, sometimes its nothing at all and its just an excuse to make your audience jump in fear and don't worry about that fear being fleeting, it'll stick with them the whole film. No need to build up suspense because that's for amateurs forget the subtlety less is less and more is more don't worry about overdoing it.
You've seen this before, the found footage style where everything is told through the perspective of a camera in first person. This is perfect for a lower budget film because you can just hide things from the audience and give them nausea from all your jerking camera movements and lack of a steady cam because blurriness and shoddy camera work just make the movie more terrifying for all. And don't worry about the believably of someone holding a camera the entire time and not putting it down because that's completely believable.
Forget about them they're just disposable pieces on a game board that you sacrifice to your (hopefully) paranormal beast, they should be the typical archetypes (the jock, the promiscuous girl, the virgin, the idiot, etc...) and they shouldn't ever be more than that. Stop trying to have detailed characters because no one cares about that, we just want to see the monster(s) kill everyone. Who cares about the people just bring on the gore and death.
So you now have everything to make the greatest horror movie every made that will be both a hit at the box office and a hit with the critics just follow the guidelines above and everything will be alright.