Supernatural stories can include anything that isn't considered natural -- such as stories involving ghosts and hauntings -- or anything else that can't be scientifically explained. Horror writers cross this subgenre with other subgenres when they create original twists on age-old conventions to give readers a fresh story. Supernatural fiction can be a challenge to write -- but when the elements are right, your story will engage readers across genres.
Devise an original twist on an old theme. Readers of the supernatural will expect the conventions of the genre, but they'll also look for a new take on an old theme. Become familiar with what's been done, then figure out how to do it differently while maintaining the integrity of the genre's conventions. Make the reader feel the dread the hero feels. Alfred Hitchcock was a master of the psychological angle. Suppose the hero worries he's losing his mind because he sees things he knows aren't real. Nobody else sees them, either. Show the reader how the townspeople question the hero's sanity -- they shake their heads and back away, as if afraid an invisible contagion will infect them. The hero slinks away, his head down, hands in pockets and mumbles in what seems to be a strange language. Certainly, the townspeople must be right. But then, this starts happening to other people in town. When you introduce a new twist, make the reader feel what the character feels.
Write descriptively about moods and setting. These two elements are extremely important, as the supernatural genre relies on evoking a sense of dread, a sense of trepidation and a hefty dose of suspense. Some supernatural fiction also relies on the "jump" factor, but even these moments come after the previous elements have been put in place. Don't write, "Barry saw a ghost." Build the scene. Here is an example of how a first draft might go: "The hairs on Barry's neck stood on end, as if an electric charge had passed by him. He stood at attention. His breath caught. His gut tightened. He looked straight ahead. Thick fog hovered above the ground, swirling occasionally, so he couldn't be sure anything was there . . . except he knew someone . . . or something . . . was watching him." Build up to the moment. Later, after all this description, Barry will actually see what he had previously felt.
Write so that you highlight actions in your story. If someone is walking through a house, break your sentences up to pace the action. For example: "He opened the door. It creaked on its hinges as the darkness beyond became exposed. He heard something shuffle across the floor and thought about turning back, but he had come this far. He had to know what waited for him inside the house." That paragraph could be broken up to better pace the action. For example: "He opened the door . . . The hinge creaked. The darkness of the room threatened to swallow him. He took a step and froze as something shuffled across the floor. He reconsidered going in, but he had come this far . . . Now, he stepped into the darkness, ready to face whatever waited for him beyond the front door."
Keep readers in suspense for as much of your story as possible. Deliver the frights in increasingly larger doses. If you place your best work at the beginning of the story, you may place pressure on yourself to continually write bigger scares. If you follow larger scare factor elements with weaker ones, your readers will feel let down. Make each scare progressively more intense.