I suggest you see what your local library has before you buy. In my experience, most books are full of gorgeous pics but they all contain the same basic information, which is available in more detail here at SMF or on videos like Soaping 101. I definitely DON'T recommend "Soap and Candle Making for Dummies" because it has no info on CP, just MP.
Here are some I've seen recommended here:
Anne-Marie Faiola - Pure Soapmaking
Alicia Grosso - The Everything Soapmaking Book
Smart Soapmaking by Anne Watson
"Soap Naturally" by Garzena and Tadiello.
"The Natural Soap Book" by Susan miller Cavich,
"Smart Soap Making" by Anne L. Watson,
The Complete Idiot's Guide to Making Natural Soaps by Trew and Gould
If "Soap Naturally" is an update of "The Natural Soapmaking", I'd not recommend it. The authors laid down unnecessary soapmaking rules and made too many pseudo-scientific claims in The Natural Soapmaking book. By the time I'd skimmed TNS book to the end, I was grinding my teeth.
I like anything by Anne Watson. She presents soap making in a sensible and matter-of-fact way. You won't find gorgeous pictures or photo-tutorials in her books, but if you want common sense and very little "foo foo dust", she's a good resource.
I second/third the library option before purchase! I exhausted my local (small, small town) library's stock of soaping books (less than 1/2 dozen) and began ordering from other libraries via the Library Sharing system in place in our state. I expect many places have a Library Sharing system where you can borrow from a wide variety of libraries, thus finding more soaping books to evaluate.
Many of the books I read were not worth a second read, and certainly not worth ordering from a book store. None at my local library were anything more than eye candy, IMO. There were a couple I would have liked to actually purchase, so I started a wish list & periodically review that list. So far, the book I have by Dr. Dunn, Scientific Soapmaking, is the one I use the most for research. But for a beginning soap maker, it's a little too scientific. What a newbie needs is a bit more hands-on how-to-make soap.
The Anne Watson books are good resources. I also liked the books by Alicia Grosso, Cavitch, mentioned by dixiedragon above. I liked one of Faiola's books, Soap Crafting and may borrow that one again. I was not impressed with her Pure Soapmaking book, however.
Thanks for all the great ideas and suggestions. I’ve shelled out on Anne Watson’s book which I’m liking so far.
I’ve used my Kindle subscription to have a look at a few books and most looked a bit rubbishy. At least one sounded like the author had never made soap in his life (apparently commercial soap’s main bad ingredient is “Alkali” - his capitalisation - while handmade soap is full of Lye, a safe and natural cleanser! Yikes)