I think that the opening scene to Halloween (1978) is a typically great example of an original slasher movie, displaying many generic codes and conventions, and effective cinematography to achieve its effect.
The scene begins with two adolescences, alone in the house kissing on the sofa. The dark lighting of the outside establishes that it is night time, and the slow, brief pan over the pumpkin makes the audience aware that it is Halloween; which immediately has spooky and dangerous connotations that set the atmosphere straight away. The entire opening is filmed using a point of view shot in the eyes of the killer, combined with hand held camera movement to make the view seem realistic, unsteady and uncomfortable - which is effective because it makes the audience feel uneasy and very involved and up-close to the action happening right before their eyes. Furthermore, the shot is one smooth cut right up until the unmasking, lacking in any kind of jumpy editing. This makes the scene very seamless and slow paced, building up the tension gradually.
A lot of low-key lighting is used in the darker areas of the house, creating shadows and casting grey light. Where there are lamps on, the warm light is dim and shadows are lightly spread over some areas, showing how no one else is home, and the rooms are still and empty. Furthermore, as the killer approaches the girl's room with his weapon, mise en scene elements such as her frilly lamp suggest that this girl is sweet and innocent, juxtaposing against her sexual behaviour with her boyfriend and the fact she is wearing a lack of clothing. This helps to achieve the surprise of the attack, and corresponds with typical slasher conventions; such as the first victim who is often promiscuous, and the killer being masked and unidentifiable.
Lastly, the non-diegetic score is a constant, ringing high pitched shrill, which only faintly changes in key, with accompanying slow piano chords, to build suspense and tension throughout. At the attack. a loud crescendo sounds to enhance the fear and shock of the character, with the eerie ringing continuing right until the end to leave suspense lingering in the scene. The music gets more and more intense toward the end of the scene when the killer (Michael) is unmasked as a little boy, and so to emphasise this uncovering, the score gets louder, drops in key, and the camera zooms put at a high angle to display the small boy with his weapon highlighted in the moonlight. This makes the audience feel shocked, and makes the scene appear much more scarier, although the location is simply in the front garden of a normal house.