Research

I have looked into the effect Mise En Scene used in horrors

Lighting

Low Key Lighting is commonly used in horror films. Certain areas are lit up to create shadows however the rest of the scene would be very dimly lit to create a spooky atmosphere.
Along with low key lighting Strobe lighting can be used to create a sense of panic and chaos.

                                                                               

Camera Effects
Night vision cameras are often used in horrors. They give the audience point of view from the characters.

Costumes/Props/Makeup
Depending on what genre of horror film it is the costume or the props used will give the thrill of a horror. For example The Shining contains a lot of props such as axes and knifes to create suspense and tension. On the other hand films such as The Ring has used costume to create an eerie atmosphere. Costumes are typically long draping pieces of material, ripped or bloodstained.

                                   
                                       

Location

Many films are shot in far away abandoned shacks, castles, mansions, dark forests and dingy motels. As soon as the scene is set in one of these locations the audience automatically thinks of all of the connotations that these places have. When I am setting the scene in my trailer I am going to aim for a sense of isolation.