Poster Research

The five most important aspects of poster design are:

1.  Making sure your poster is readable.  Whether it be size, quality, or font a poster needs to be easy to read.
2. Know your audience and make sure to adapt your poster to best fit this audience.
3. Poster need to have a layout that is well organized and not distracting or hard to follow.
4. Information on posters needs to be as concise as possible while still conveying the important messages
5. Posters should be visually appealing with easy to read font colors and texts and an appropriate design for their purposes.
www.ext.colostate.edu/staffres/poster.pdf
 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1876493/

Here are some good examples of Poster Design:
 
 Image Source:
www.mathaware.org

  
Source:   collider.com

These posters are well laid out, contain just the right amount of text (which is easy to read) and convey their message concisely and efficiently.