Conventions of a thriller

Chris and Nikki in media :)
Missing ollie great amounts and his input, but the show must go on

Most thrillers play on the ideas of voyeurism, which is the idea of watching, or being watched.
Most openings of thrillers utilize dark, dim lit interiors, also playing on the idea of building suspense
The sound tends to be quite eerie, dramatic, high pitched, suspense building
There is little if any dialogue but they often use sounds over the top of the music like a metronome in se7en, or related sounds like a shutter of a camera in one hour photo
The editing involves a lot of cross cutting in shots so as to build tension and keep the viewer on edge, because you're being overwhelmed by perspectives
Some thrillers like to use flashbacks as an opening scene, and cross cutting from happy scenes to sad, intending to throw the viewer
Quite often the main plot of a thriller is involving murder, so they use a key event such as a death to set the movie in motion, and it is often the person you would least suspect
They go for the psychological impact and sometimes focuses on why and how, as opposed to finding out who the killer is, if we know from the start.