I take a look at subtle horror, partly by focusing on things that have chilled me as a reader. That's pieces by Ray Bradbury, Robert Aickman and others.
The focal piece is the 1902 story from W.W. Jacobs called "The Monkey's Paw," a tale to which I said "meh" when I first read it as a kid. It's deceptively simple, and I don't think my junior high imagination was fully engaging with the story, though its brief arc has always stayed with me.
It was really when I transcribed a portion of it a while back that I came to appreciate its brilliance. Very little is "on stage." Much is in the anticipation of a potentially walking corpse that's in a badly decomposed state...
It gives us something to worry about a bit. Wishes with the monkey's paw of the title always go wrong. It seems to confirm that with the first of three wishes in the story. Then it lets things roll along on a cold dark night.
And possibilities are introduced that let the reader's imagination work, possibilities and a little waiting.
There's a wish, a look out the window but...nothing. Then in the dark hours of the night, there's a sound at the door and then a knock an then a little more, coupled with different opinions on whether to answer or not and other bits of dread.
It was fun to do the presentation for a big room. We turned the lights down and had a campfire-story experience.
What does the story offer? A few points to keep in mind:
Atmosphere...a house that's become cold and dark and isolated.
Something to think about...the son who's been summoned back from the dead has been in the grave a while and was badly injured at the time.
Something to worry about...Monkey's Paw wishes don't turn out so well.
Anticipation...At first there's nothing after the wish, but a little while later there's a sound.
Implication...The sound turns in to a knock at the door, a knock that persists and the clock starts ticking as conflict bills. Do we wish the visitor away or open the door?
Sometimes as Stephen King said in Danse Macabre, you gotta show the monsters.
But maybe it's not a whole story you need to compose but a scene. Could the same elements be deployed? I think we see that in play in the log of the Demeter in Dracula, a small but chilling portion of a bigger tale and in many other effective moments in the horror pantheon.
I'd say try these points somewhere along the way and invite readers or viewers to engage.