Infographic design Tips

Edward Tufte's books are by now classics of information visualization. Aside from being beautifully produced, they are full of useful discussion and examples about good and bad ways to represent information.

The Visual Display of Quantitative Information Envisioning Information Visual Explanations: Images and Quantities, Evidence and Narrative (haven't read this one) Beautiful Evidence (haven't read this one)

http://www.edwardtufte.com/tufte/index

I second Josh Simons answer; Edward Tufte is a great place to start. I have also found Stephen Few's work to be very helpful, particularly around dashboard design.

http://www.perceptualedge.com/ - Stephen Few

The 4 Tufte books are classics. I somehow noticed when the first one was published and reviewed. I subsequently purchased the others when they became available. The key message of "let the data speak" was very relevant to many business issues when I was in automotive engineering. I went to Tufte's seminar more than once and took several associates with me. The seminars are very enlightening and Tufte is an outstanding speaker. All of his books were self published just like Cool Tools and he did sell them out of his garage at the beginning. He hates Powerpoint and is not afraid to point out the deficiencies. These books are very useful to anyone that needs to present complex data or critical information.