In order to get an idea of conventions in film posters, I have tried to look at a range and analysis what I think is effective and what conventions are normally followed or sometimes broken.
My analysis of newmoon
After looking at various different film posters I have concluded that these are the common conventions that I should either follow or challenge:
Film title
Main actors names usually above, below or opposite an image of them from the film itself
Awards that the film has won along the top or bottom of poster
Image taken from the film (either a character or place)
Colours relevant to style and genre of film.