How to write a psychological thriller

Because the film we wanted to create was a psychological thriller I thought it would be important to ensure that we followed some of the rules of how to write a psychological thriller, so that our film was true to it's genre.

When writing a psychological thriller it is important to ensure psychological and action aspects are incorporated to add suspense within the film.
 It is also very important that the audience is able to fully understand the characters, as in psychological thrillers it is important the audience is able to understand the character, more than the plot in some circumstances. This is because psychological thrillers reverse the thriller theory of 'plot over character'.
It is also important that in a psychological thriller the character doesn't win with physical talents or efforts but instead by using their brain, with wit and intelligence.
It is also important that a psychological thriller involves elements of drama, mystery and horror. This is because psychological thrillers focus most on a characters mind and motivation therefore those factors help bring emphasis on this.
Life and death situations should also be added to help create a climax in the storyline this would then be used to show the values of the 'hero' rather than a threat to the 'hero'.
 Psychological thrillers often involve common themes such as the following; death, reality, perception, identity, existence and purpose therefore it is important that these themes are used in psychological thrillers.
it is also important that the motives and intentions of the 'bad guy' in the film are clear as they are key to a psychological thriller. This is because in a psychological thriller the motives and intentions behind the 'crime' are considered more important than the crime itself.
Lastly it is important that the story focuses equally around the 'hero' and the 'bad guy'.