After analysing, horror film trailers, I have listed a variety of things that appear to be in all horror film trailers and that are essential to have in our own trailer, in order for it to be successful.
These are the main conventions that make up a horror trailer:

Dark atmosphere (Mise-en-scene) The right setting is essential to the horror genre. This includes lighting and also the locations. The setting is a important feauture of a horror trailer as they usually give an indication as to the genre and type of horror it is(e.g ghostly, sci-fi, realistic killings). These locations usually include: forests, mental homes, graveyards, haunted buildings or places where something previously has happened.

Editing is usually sharp with short shots usually no more than a few seconds. This builds up tension and suspense luring the audience in to watch the trailer and want to see the film.
The editing usually increases in speed along with the music, building up to the climax, title and release date of the film trailer.
The music and sounds often begin at a slow tempo until a major event takes place. Now in a state of disequilibrium (Todorov) it now becomes more aggressive and upbeat.

There is usually a villain(Propp's theory) present in the trailer sometimes wearing costume, which is also a significant element of a horror film and can become an image that represents that film which audiences will remember. Other charcters normally wear everyday clothes to show their normality againt the villian. These other charcters include the victims, and any one else featured.

In my group, these things will be taken into consideration whilst creating our film trailer and use them to the best ability possible. In my group there is one other person. I believe this will work more efficiently than a larger group as we can divide the work equally and be entirely sure as to what we are doing.