I led a session on selling your work digitally, and mentioned a few resources there that I thought were a great places to start – start – learning more:
Jane Friedman’s Five paths to publication helps break down the confusing array of choices into something useful and meaningful.
Digital Publishing G+ group, founded by Evo Terra, is a well-moderated and high signal-to-noise ratio G+ group filled with people who are interested in the best ways to sell digitally.
The Book Designer (Joel Friedlander) and Kris Rusch are consistently well-thought out and informative. I sometimes disagree with their conclusions, but I always respect their arguments.
My instructions on how to sell your eBooks yourself (and in person).
This isn’t a comprehensive list – not by a long shot – but I these are five high-quality places to start.