Some writers prefer to work from notes rather than from a draft of a paper because they see the full draft as too dense or detailed to revise for a poster. Especially for a general information poster, you may prefer to move from notes directly into drafting chunks for the poster. If you draft from notes, be sure to state the key pieces of information that need to be included on the poster. Focus on those key points and work back and forth between key information and possible headings that cluster the information. Question yourself about audience and focus over and over as you flesh out the chunks of your poster. And then move into revising to be sure that you have included clear and appropriate information.
