1. Read Scary
Half of a writer’s job is to read (what a great profession)! Edgar Allen Poe, Shirley Jackson, Stephen King, Flannery O'Connor are all good writers to start with.
2. Have a Highlighter
Highlight parts of the story which scare you out of your mind. Ask yourself, what about makes it scary? What gets your pulse rate going? Most importantly, ask yourself why.
3. Pick a Plot
Inspiration is everywhere, but the internet is a treasure trove. One news item I came across was about a couple high on drugs and got arrested for selling tickets to heaven. Not only was I fascinated by the fact that people actually bought these tickets, it gave me an idea for a short story about a man who wins a ticket to heaven.
4. Observe People
I meet people on a daily basis who would make a good antagonist. In most cases you won’t even need to exaggerate. Stick with using strangers, but if you use somebody you know, make sure you change their characteristics/features enough so they won’t recognize themselves.
5. Interview your Monster or Murderer
Imagine you’re a reporter and you’re assigned to interview your monster or murderer. What questions would you ask? How do they respond? Do they reveal anything that would really make your hair stand on end?
6. Life should start off as Normal
Your monster may not be real, but your main character’s life needs to start off as normal, otherwise the reader will have a hard time relating to the story.
7. Pace Yourself
As you start writing, make sure you alternate short sentences with longer ones. This gives the reader a chance to be surprised and also helps you build some tension in the story.
8. The Devil's in the Details
Or lack of… don’t expose your monster all at once. Often when you watch a horror movie you only see parts of the protagonist. It’s not until the end that we see the horrible creature in its entity. The same should go for a short horror story. Sometimes not knowing is scarier than knowing.
9. Give People Time to get Scared
Build suspense slowly. Note the difference between:
A man walked in and killed everybody.
It was three o'clock in the morning and we were sitting on the sofa watching a horror movie, when there was a knock on the door. Instead of answering it, we clung to each other in terror. A few minutes pass and we began to relax; thinking whomever it was must have gone away, so we continued watching the movie. Then there was a tapping on the window behind us. We froze in terror. Who was behind us? Who wanted to come in? Yet, somehow we couldn’t turn around. As dreadful music flowed from the television there was another knock on the front door. But this time it slowly opened and a man came in with a gleaming ax and I knew he meant to hack us alive.
10. End with a Twist
Your reader will be disappointed if he predicts the ending. So keep them guessing and end it in a thought provoking, unexpected way. Never use, “I woke up and it was a dream” for an ending or you’ll lose all credibility.