A Decent Proposal, by Rhonda Whitton and Sheila Hollingworth, Common Ground Publishing, Altona, Vic 2001 (New edition 2011 from Keesing Press : I'm talking about the 2001 edition because that's the one I found in the library.)
An Australian book on how to write book proposals! It's gold.
First, there's the information that book proposals are a necessary part of getting published. Who knew? Not me. I thought only writers of non-fiction had to worry about that sort of thing. Turns out, they are a really good idea even if the book is already written: The proposal is not to write the book: The proposal is that the publisher publish it.
Second, there's the information on how the proposal should be done. Should there be a cover letter? How long should it be? What should you say about yourself, if anything? How long should the synopsis be? How do you figure out what publishers to approach? - For some people that last question is a no-brainer, you look for books of your genre or whatever and see who published them, but you'd be surprised, we're told, of the number of hugely inappropriate books that end up in a publisher's slush pile. In fact, a lot of those questions you see on different writing blogs about how to approach a publisher are answered in this book.
Thirdly, A Decent Proposal has examples to illustrate what the authors say. This important because some of what they say sounds a bit intimidating at first. Once you read the examples, though, you see that it's not actually so hard. All you really have to do is keep taking those steps one at a time.
Finally, although most of the information in the book looks applicable to anywhere, it's great to find something that's especially applicable to Australia.
Definitely worth checking out.