Following the old adage "less is more" can improve your website or blog. Graphic artists generally recommend as much white space as possible; hence, the creation of "Minimalist WordPress Themes."
Studies have proven that the eyes "bounce around" and visitors fatigue quickly (i.e., leave your website, blog, or ad) when there is too much to look at on any given page. Take any popular magazine and look at the ads on the back cover or inside front cover spread. You'll probably see a lot of space with little text. Be careful, some of the ads are image or branding ads, which are not used to incite action by the viewer. Include enough content to make your message concise, clear, and visually pleasing, but don't over do it.
Additional info can be found at this site: Minimalistic Design at Simpl(e)y Done (also recommended reading by Plaintxt.org)
For a comprehensive list of WordPress Themes, visit Emily's site: How to Blog: Comprehensive List of WordPress Themes