Main factors in a film trailer:

It's vital not to over use key factors for a film trailer such as - shots, editing and mise-en-scene, because it would definately lose it's effect.

1. Equipment & Technology - to construct meaning. For instance: Computer Generated Images - fantasy movies - surrounding, sureal locations. Camera - different angles, shots, editing - pace, style, sound - non-diegetic/diegetic, genre.

     2.  Symbolic - 

• Created beyond what is obvious to see (for instance) - specific facial expressions, mise-en-scene

     3. Codes & Conventions - specific to film trailers

•  A firm set of rules & way of doing things.
• Can slowly adapt.
• Shouldn't be challenged on too great a level. 

         The reason for them;

         1st - Allows the audience to become familiar with a certain genre as they become
                 accustomed to seeing certain things.

         2nd - It ensures that a certain text works well & fits into it's genre.

     4.  Camera - variety of shots depending on style.

• Perhaps even ECU of lips.
• Crane shots - hovering over stage.
• Low angles.
• Establishing shots of location - where the film is shot.
• Tracking.

     5. Editing & Sound

•  There are many different editing techniques used in film trailers:

          - film trailers usually features editing. For instance if someone is stabbing someone, that cannot   possibly be done in real life, therefore the fast pace editing is done in order to create that atmosphere.

          - non-diegetic music is usually used to match the mood and atmoshpere within the trailer to suit the genre.

          - spit screens/CGI.

          - choosing to include diegetic sound. For instance - The script.

          - changes in levels of sound - to create tension.

      6. Mise-en-scene

• Can vary greatly depending on the genre of the film trailer. Since, I'm producing a Romance/Drama trailer, it will contain long shots of a restaurant to establish that someone's on a date, since restaurants are well known for dating.
•  Props - table, wine glass.
• Costume - certain outfits. (Feminine and masculine)
• Location -
• Facial expression - sad, gloomy - related to lyrics of the chosen non-diegetic sound/music and script.