Hi! Just like...
The real horror is when someone realizes--when it is too late--what they've led themselves into.
...I think that sums it up a bit.
Although you can break this down into different types of approaches or I would also say
resources that allow you to reinforce the meaning of a story. I mean, rather than focusing on the horror itself, I would recommend that you
keep in mind that first of all what you are telling is always a story, and as such it must first stick to all aspects of its creation (argument , characters, setting, descriptions, etc.) And then, only later, introduce the subject of horror. But I advise you not to confuse the story (the what) with its treatment (the how).
Because we agree that currently it is very difficult for something to scare us. In fact, they already realized that when they made the Hammer movies in the 40's, although, naturally, due to technical limitations. Since the special effects of then did not have the immense render capacity that is available now, that forced producers to strengthen other aspects.
This, of course, was also reflected in the literature.
What matters is knowing how to tell a story well even if the subject is somewhat hackneyed. Because, as today's productions no longer impress us much, readers are also skeptical, reacting favorably to "other elements."
Take, for example, the case of the film
The Keep, by Michael Mann, but rather the Francis Paul Wilson novel on which it is based.
Molasar, the main villain in the story, at first glance is like a poorly made Eddie. Indeed, it is not scary. However, the strengths of the story are not in that character, but in the aspects of the plot and, above all, the dialogues. Also, here is an example of an approach that has not been discussed before: a ghost story with soldiers.
In the YA novels about vampires and werewolves, romance is more important than the terror of the stories.
You have the cosmic horror of Lovecraft, or rather the suspense than terror of the eternal Poe.
What scares from the
Alien series is not so much the monster itself, but the weakness and arrogance or human greed that sometimes makes us be more monsters than that same biped dolphin-like shark with two-jawed. One as a spectator is more afraid of human precariousness (it is not gratuitous that the woman several times is almost naked or with a stomach full of staples or brackets as in
Prometeus while facing the monster).
That series teaches us that almost most of the time everything goes to hell and allows the monster to make its own due to the betrayal of a human.
Hitchcock, what I can telling you? Master of suspense. The scene of
Psycho in the shower is still one of the scariest ever filmed.
For all of the above, I insist that,
more than telling a story, you have to know how to do it. For example, you don't need to have a scary monster; what your reader will really fear is that you put the characters on the spot or situation that you make them face other characters who serve as rather obtuse and unpleasant adversaries. For example, in all the scenes of Germans and Jews, what really scared you was not the officer in black, you already knew that he was bad, but the civilian on the street who accused and / or betrayed an innocent.
There human incomprehension is the true evil that scares you.
In
The Exorcist (which is also based on a book, Legion),
what is scary is helplessness, the feeling that, yes, maybe in the end we win. But meanwhile we are going to see them fall of all colors in front of an ancient and powerful enemy.
In
Shark, more than the fish, it is suspense management. That's incredibly better dealt with in the eponymous novel. Again
the human precariousness this time in the form of an old and somewhat unsuccessful beach policeman forced to become a hero and also in a field that does not dominate, the sea.
I hope this helps.