The Writer's Guide to E-Publishingis a website with an array of resources and been-there-done-that advice. In a blog-style format, with contributions from lots of different writers (including the marvellous Talli Roland), it's easy to lose a lot of time browsing here :)
Self-Printed: the Sane Person's Guide to Self-Publishing (2nd edition)read which outlines clearly and specifically exactly what Catherine Ryan Howard did (and does) when self-publishing her writing. Her advice is thorough and comprehensive, if a little bossy at times (but hey, it's her book, so why shouldn't she get bossy?). Publishing to Kindle and Smashwords are explained step-by-step, as is using Createspace to produce a paperback. She also covers how to sell and promote (in a non-annoying way...) using only free online tools such as an effective blog and social media presence. I found the answers to lots of nitty-gritty questions here, and would strongly recommend it to anyone thinking about self-publishing.
I particularly enjoyed her frank discussion about the quality of much self-published writing and her attempt to distance herself from the more rabid self-publishing rhetoric (usually focused on 'gatekeepers' and the many perceived failures of traditional publishing). I read in it the kindle version, but it is also available as a print on demand paperback.
It's also well worth checking out Catherine's site for more advice and opinions about successful self-publishing.