One feature which can be seen in the genre of thriller/horror is the use of close ups. These are used frequently in this genre to create a sense of mystery for the viewer as they want to see more of what's around the subject being filmed, and it also allows the viewer to see closely what is wanted to be seen, or what emotion a character is showing.
Another feature which is used frequently in this genre is slow panning movements. These are used to show the viewer what is going on in the scene, but it's slow to make them want to see more in a shorter amount of time. These are usually used, as well, to introduce a surprising section of film when the audience is subject to something shocking or unexpected. This is used to introduce this because it allows the audience to see the whole shot or setting and make them believe that they know exactly what is in that establishment, and when something appears that they weren't aware was there, it create an even more effective action.
Dutch tilts are used in this genre as well. These are used to adds a sense of confusion for the viewer and to make it seem disorientating. This adds a sense of realism or connection between the audience and the characters on screen as they get to experience or see what the character is seeing or feeling. This is effective in the way that the viewer gets more involved in what is going on, which in effect, makes them more interested in what is going on.
Another feature which is often used in thriller/horror films is low angle shots. This is done to make someone appear small and helpless. It is a convention of thriller/horror films because in these types of films, more characters are in a weak position, and the use of the low angle shot helps the viewer recognise their position.
Editing
One thing which is used in this genre is shot/reverse shot. This is used in most other genres as well, but it is used to show the conversation between two people or their relation or positioning to each other. The shots included in this feature as usually point of view shots, which are used to show the audience exactly what the character on screen is seeing and to make them feel included in what is happening.
As well as this feature, montages are used to show this genre, again with most other genres as well, but they are used to show the audience a lot of the film in a short amount of time. This is done so that they are aware of the narrative of the story and become more interested in it, which makes them want to go see the film.
One thing that is included in most thriller/horror trailers, is the use of fast paced cuts. These are used to create a panicked feeling and to create the feeling that things are going to happen quickly, even though you don't want them to.
Another feature added into trailers of this genre is match on action. Again, this is used in other trailers as well, but is used in this genre to show the result of something, usually bad, happening. Although this is true, some times in trailers of this genre, match on action is not used, in such situations as something has happened and they are not showing the result. This creates the sense of mystery, and encourages the audience to want to see what happens.
Sound
One feature which is used in trailers of this genre is the use of dialogue. This is done to show the emotions and thoughts of the characters on screen to allow the audience to know what is happening and what effect it is having on the characters.
Another feature which is seen in thriller/horror trailers is the use of a voice over. These are used, again, to show the audience what is happening in the film, but also because it's an easy way to get the to know as they don't have to watch reels of the film to understand, instead they can just be told.
Non-diegetic music is a feature of trailers of this genre as it creates a certain atmosphere, depending on what atmosphere the producers are trying to create. The use of non-diegetic music can be used for other reason as well, such as introducing a place or character which may have ties with the music being played, or it could also be played to introduce a new scene, where that particular music is being played in the diegetic world.
Non-diegetic sounds are also used to help create the atmosphere in certain situations. For example, when there is a tense or anxious moment, some types of instruments such as strings, or the beating of a drum could be used to make the audience feel what emotion is suitable for the atmosphere which is being attempted to be made.
Mise-en-scene
Usually the setting is a dark and spooky place, for a horror, or somewhere 'normal looking' for a thriller, which has the potential so easily turn into some where spooky at certain times of the day i.e. night time. The reason this is, is because most people associate scary or bad things happening when it's dark, and so using this in films allows them to quickly link certain situations together.
The costume of most of the people in thrillers/horrors is usually just normal clothing that you see people wearing everyday. As in, different stereotypical groups of people's clothing as well as people just wearing clothing which you can't really group. This is done to make the audience think the film is closer to reality then to any made up world, by putting people from all walks of life into it.