Great getting started reading:
Data Visualization for Human Perception by Stephen Few
Counterpoint to Tufte
The “Chartjunk” paper at CHI
Be sure to read the Cleveland an McGill Graphical perception paper (short version for 638, long version for 838). And maybe a more modern follow up
infographics design post: some makes me mad, other is good – makes you realize what these people are about
http://www.smashingmagazine.com/2011/10/14/the-dos-and-donts-of-infographic-design/