Conventions of Film openings

Titles: Production company logo, Actors, Editors, Scriptwriters, Producer, Music composers, Film studios, Director.
Establishing shot: Shows location, first introduction to setting and characters with some possible action. Establishment is often re-called by an extreme long shot. Sometimes the shot may have a text indicating the location and the time film is set.
Protagonist: Film openings generally include the main character and try to give the audience an impression of the characters personality and motives. Sometimes there are support characters that may appear with the protagonist.
Music: Reflects the mood and genre of the film. For example, fast paced music for an action film. It allows the audience to feel empathetic to the movies plot, character and world.
Incident that sets up a larger narrative: For example, if a characters friend is murdered it can be developed into a more complicated storyline. Thus triggering different events to occur, such as contemplating to avenge his deceased friend.
Voice-over: Often the protagonist explains what may be expected later in the narrative or what may have happened in the past. There may be an omniscient narrator telling us the event's regarding the past, present and future of the film.
Mid-Action: The opening sequence can often start mid-action.