Conventions of Twilight Trailer

After watching the Twilight Trailer, I noticed lots of conventions that were used. The trailer switches from clips of the movie to endorsement. There was an intense soundtrack, hinting to the audience about the tension in movie.
Instead of the same continueous pattern of clips and endorsement, the director added dialogues. The dialogue that the director chose hints to the audience about the genre of the film, but with a little bit of enigma to persuade the audience to see more of the movie.
Without watching the movie or reading theb leaflet, this trailer foreshadows to the audience about the genre. There were clips of a girl and her dad, telling the audience that it's a family movie; a boy and a girl making-out, showing that it's also about romance, and a repeated dialogue of the word, 'vampire,' which shows that this is also a horror movie.