Ensure you follow the poster conventions for your own artefact. The major forms and conventions of film posters could include: A large title which attracts the eye, bold colours which stand out from the background, intriguing picture which would attract viewers to the film, persuasive language which might persuade the viewers to go and see the film, using the main character's name for promotion, and the certification will either to ensure that the right type of people are watching the film. Try using either the rule of thirds or the triangle of interest as a format for your work. Have a look at this site http://www.colorpilot.com/comp_rules.html for more information about how to use the rule of thirds. A successful film poster will accomplish attracting the target audience and persuade them to come and watch the film