I found Dictate Your Book: How to Write Your Book Faster, Better, and Smarter by Monica Leonelle to be a useful resource, although it really is just for the beginner in dictation or for those writers who are just considering dictation but haven’t yet tried it.
By the time I got around to reading Dictate Your Book, I had already learned most of the information from other sources (web pages, blogs, and podcasts) and had started dictating on my own months before.
That said, there are a lot of useful tips in the book, most of which come down to instructions on how not to waste time training your software until you decide that you really want to use it full time.
The one thing I wish Leonelle had covered was the use of a combination of voice and the mouse and keyboard for certain tasks. For example, you can edit with Dragon. Sure, doing it by voice would be completely thankless, but if you add in your mouse and keyboard for cursor placement and other tasks, you can edit at about the same speed as you would by keyboard. I have done as much myself.
I’m glad there are books out there like this, though, that give writers like me options for increasing their writing speed without spending more time at the keyboard.