The main function of a poster is to capture a moving audience with a message. When designing a poster, plan its design carefully. You will have a short amount of time to attract and hold your readers attention. Think about the one aspect of the information that must convey the message and plan your design around that.
After you determine the most important information, think about the imagery that will best convey your message visually. Should you use on large image, or have several small interesting shapes? Would bright colors evoke the mood or emotion that you want? Should some of the words be in very large type to be easily read?
It is also important to know what type of format will be used. What size will the poster be? How big or small? That will help you with the placement of imagery and text.
Also consider where the poster will be displayed and what size and shape it should be. Explore alternatives with thumbnails to find the most effective and dynamic visual imagery. Eliminate any superfluous detail. Work out the right size and placement for everything on the poster. Because you are usually working on a large scale, pay careful attention to balance and proportion.
A poster should: