If you want to write good scary scenes I suggest you take the time to scare yourself, and notice the effects you get. I go for walks down the dirt roads around my place at midnight. Sometimes with the moon and sometimes not. There are trees on every side. I hear night birds. But there isn’t a single streetlight. Once in a while you’ll see a lonely house lamp through the pines, that faint fog of a light that only serves to accentuate the greater darkness all around.
Shadows follow me when the moon is up. I hear small animals crashing away through the brush, but they don’t sound so small when you’re standing alone on a rutted dirt road with the dark forest all around. I don’t know if this will work for you, but it gets my heart rate up.
Use your own actual experiences of fear. Create new experiences. Write them down without holding anything back. This is the secret to generating the emotions of fear, terror, and horror in your readers.
Sow with darkness. Reap by the light of the moon.