The document discusses key conventions for comedy film posters, including featuring close-up shots of the main characters' faces at the forefront. Facial expressions are also important, as they can instantly portray the comic genre, such as Seth Rogen's witty smile in one example poster. Learning about these conventions helped the author plan their own film poster by thinking carefully about the main image, character positioning, and using facial expressions that aim to portray a theme, such as doubts, as shown in the poster for "Johnny English."