>>13610 (OP)
>a simple question: how, exactly, does one create a good horror story
Frustrating, I know. The question is not simple. The challenge is found in mastering your chosen form while admitting that no artistic form can be completely mastered. Two things are required from you, kindly honesty to oneself, and the enjoyment of the challenge.
To scare an audience one needs to use what scares them. Within this stupid tautology lies the not so stupid crux of the problem. Take a look over my shoulder and see what I found horrific at one time or another.
The War of the Worlds 1953 movie. Sneaking down to the den on a malicious dark and windy late October night to catch this may have helped. This film gave my seven-year-old self nightmares for months on end. I could not stand near a simple streetlamp either without feeling uneasy, being so suggestive as they were of the sinister goose-necked Martian heat ray weapons. Today, all this invokes is nostalgia.
A Nightmare on Elm Street did it too, but did not carry through with such a lasting impression to my teenage self. It was a very in-the-moment experience. Today, the whole slasher franchise is more of a form of comedic entertainment, although I am not so far gone as to find myself rooting for some sadistic villain as I've found so many others cheerfully do.
The last frightening full-dress novel remembered by my adult self would be Warday, which was a plausible and realistic presentation of what might still someday be.
What, today, gives that visceral twinge, that drawing back from exposure to a story I suspect may become an unwelcome reenactment in my dreams? A writer's adolescent reflections serve. Vidal, Bukowski , even Louis Auchincloss. Now, compare such with a newspaper story of childhood soldiers, twelve year olds armed with AK-47s, unleashed to do their gleeful voodoo on some defenseless village. The stories of both groups are absolutely real, and both are far removed from daily experience. We need not dwell on relative horribleness. I assure you I am otherwise sane, and being such I do not equate the nightmarish aspects of both sets as being anywhere on the same level. Yet … one is evocative as the other is not. It leaves a little nagging question for you to ponder: what is horror?
Two bits of advice I will leave you with. First, Danse Macabre by Stephen King is required reading. Second, try writing for a younger audience.