1. The uncanny valley
"The uncanny valley is a concept first introduced in the 1970s by Masahiro Mori, then a professor at the Tokyo Institute of Technology. Mori coined the term “uncanny valley” to describe his observation that as robots appear more humanlike, they become more appealing—but only up to a certain point. Upon reaching the uncanny valley, our affinity descends into a feeling of strangeness, a sense of unease, and a tendency to be scared or freaked out. So the uncanny valley can be defined as people’s negative reaction to certain lifelike robots."
2. Monster as metaphor
Try to link the monster to an emotion or problem the character is facing. This can be more powerful than a menace randomly running around wrecking havoc.
Use all 5 sense to describe the monster or a dramatic scene.
Develop tone within the story - examples may be a particular color palette, particular emotions, particular style of language for the characters, developing clear settings that fit well together.
5. Light with dark - juxtapose scary with humor
Remind the audience that the characters are human by interspersing moments of real life, humor, the mundane, the realistic. This will make the moments of horror stand out.
6. Build suspense
Do not reveal the secrets of the story right away. Build up anxiety, dread, and other feelings through clues or near 'misses' between the character and the 'creature' or horrific element in your story.
7. The MacGuffin
Learn from the master of cinema Alfred Hitchcock about the MacGuffin.
What Is the Horror Genre?
"Horror is a genre of literature, film, and television that is meant to scare, startle, shock, and even repulse audiences. The key focus of a horror novel, horror film, or horror TV show is to elicit a sense of dread in the reader through frightening images, themes, and situations."