

The author summarizes the key points in making an effective poster, drawn from various "how-to" guides:
- The title should be short, large-font, and results-oriented to attract attention.
- Build visual elements to convey your message (photos, graphs, diagrams).
- Minimize the use of text.
- Use large, easy-to-read font. (I personally use a sans sarif font such as Verdana or Arial. Check out the following sentences.)
- Fonts make a huge difference in appeal. (Arial)
- Fonts make a huge difference in appeal. (Verdana)
- Fonts make a huge difference in appeal. (Times)
- Fonts make a huge difference in appeal. (Georgia)
- Use appropriate headers to organize and break your poster up into sections.
- Prepare a stack of summary handouts so that people can take with him.

- Overall appearance
- Amount of white space (less is more!)
- Text-graphics balance
- Text size
- Organization and flow
- Author identification
- Research objective
- Main points
- Summary
Also in the references, there is an useful website by Hess, Tosney, and Liegel on "Creating Effective Poster Presentations: An Effective Poster". There are annotated examples of effective and not-so-effective posters.
Reference:
Hess GR, Tosney KW, Liegel LH. Creating effective poster presentations: AMEE Guide no. 40. Med Teach. 2009 Apr;31(4):319-21.