What Makes an effective horror opening sequence?

From my research i have found that the following areas make a effective opening sequence:

Camera Angles – Can be used to set the scene using establishing shots, Establish whether characters are weak or powerful by using high and low angle shots, or emphasize certain points of interest or cause tension for example the extreme close up of the protagonists eye in saw.

Editing – Fast cuts can be used to create tension or action, where as dissolves and fades can support a intransitives narrative or a characters death.

Lighting – High key lighting can be used to make a scene feel very normal and friendly where as low key lighting can cause a sense of mystery and tension.

Sound – can be used to create a sense of anxiety or make the startle the viewer a good example to this is the 28 days later opening the Non-Diegetic music builds and then startles the viewer with a Diegetic car alarm.

Iconography – is used vitally within the opening sequence it is often used to identify the genre of the film, props such as knives and masks are common with horror films.

Characters – are the main focal point of the story they can either promote the narrative of the film or be used create tension such as “monster fodder ” the majority of horror films will have a antagonist a protagonist and a final girl.
Settings – Of isolation are often used to unbalance a films equilibrium horror films are usually set in abandoned places such as the mansion in the woods in scream or post apocalyptical London in 28 days later.

Themes – Common themes within horror films are death and the supernatural they often make the characters binary opposites for example the psychopathic male killer in scream and a teenage girl in scream.

Structure – The job a of a horror film opening is to unbalance the sense of equilibrium this is often done by killing of some “monster fodder ” within the first few minuets.