It might sound like an easy task, creating a great poster, but once you get into the nitty gritty of designing a research poster, you might succumb to a handful of bad habits that naturally occur when telling someone about your life's work. I call these bad habits the "sad six". Horrible posters are...
(1)unorganized.
(2)cluttered; remember, you want your viewer to ENJOY their experience, so make your poster easy to navigate.
(3)extremely confusing to those outside your field of study (I'll talk later about knowing your audience).
(4)filled with superfluous text. Remember that in addition to your wonderful poster hanging on the board in that hot, crowded room, that you yourself are also there to TELL the viewer about your work. Don't fill your poster with so much text that you become redundant. Most people would prefer to sit back, relax and listen to you tell them about your work while they look at pretty pictures, than to read thousands of words, in too small of a font, while inebriated.
(5)picture-less, posters without pictures suck, they're boring, and usually lead to people walking right past you and on to prettier posters.
(6)embarrassing to your colleagues, your school, and your lab.