Data Stories is a great podcast that just got started earlier this year that focuses on data visualization. The most recent episode from the podcast, posted last week, focuses on the use of color. A number of good points were made, the key for me to take away if nothing else… make your visualization work in black and white first. If you can design something that is meaningful and attractive without using color, you have truly accomplished your goal.
Listen to the whole podcast here: http://datastori.es/episode-7-color/