In many circumstances I experienced how powerful maps can be because a key decision maker just enjoys looking at a beautiful representation of facts instead of reading 10 pages of text. I have a background in geography, and we learned GIS software at the university, however the courses never discussed in depth aspects of beauty and aesthetics.
I would like to learn, however, more about what makes a map really beautiful and I'm searching for literature/blogs/websites/courses etc. Aspects like color choice, fonts, layouting for different formats (web/print) should be discussed. Basically it goes into the direction of graphic design but in the field of GIS and based on the possibilites of GIS software (preferentially QGIS).