The Decorated Journal by Gwen Diehn is a book that focuses on art journalling.

The book is divided into sections, the first is an extensive exploration of the different materials used in art journalling including paper, pencils, paints, pens, glue and other commonly used materials. This section is, to my mind, the strongest in the book. It contains handy tables that show the advantages and disadvantages of different types of glue, a section on the paint colours you'll need to be able to mix a good palette, lots of information about the different grades of paper, explanations of the properties of various different materials and clear advice on what to buy and why. There's even a page on making your own ink and paint from naturally occurring pigments that you've gathered! I also like the way she emphasises investing in a few well chosen, quality materials rather than getting suckered into buying endless new products that are actually quite limited in scope.
In the second section of the book, Diehn describes different types of journalling. She categorises journals into 7 different types and provides techniques that she thinks are particularly appropriate for each. I wasn't totally convinced by her categories and most of the stuff I objected to occurred in this section.
The third section of the book is called 'Pages In Stages' and Diehn splits the working process into 'starters, middles and toppings'.explores how to work with the different levels of the page through techniques like layering, collage and using text. This is one of the shorter sections in the book since it's basically reprising things that have already been described in earlier sections.
The final section of the book deals with some basic bookbinding - Diehn is a big fan of making your own journals so that you can control the size and type of paper and she demonstrates how to make several simple handmade books plus how to customise existing journals and reuse the covers from old hardback books. I have several other bookbinding books already so there wasn't a whole lot here that was new to me but the information seemed clear and competent and it's obvious that it's something she's passionate about.
Although there is undoubtedly much of value here, this is not a book that I can wholeheartedly recommend. The main problem I had with this book was Diehn's tone, which I found overly lecturing and didactic. It's very clear that she feels there's a right and a wrong way to do things - for example, she assumes that paper buckling is always to be avoided but personally, I've found that buckled paper can be an interesting design element on a journal page rather than a problem.
Sure, it's important to learn 'the correct way' to do things and I can understand her desire for 'good practice' but I also felt she could have recognised that art journalling is an expressive, experimental and free space for the artist, where the rules don't always need to apply. It's not that what she says is necessarily wrong - I agree with many of her opinions - but the way she says them invariably seemed to get my back up. Reading her words made me feel as though I was back at art college again. This isn't surprising since Diehn is a tutor at an art college but I didn't find it at all helpful or inspiring. Since I'm currently trying to unlearn quite a few of those art school conventions, I don't need this approach. I took particular exception to her saying things like "you have to earn the right to draw the details": I think that's a staggeringly unhelpful thing to say to anyone, whatever stage of drawing they're at.
In addition, I wasn't particularly blown away by the journal pages shown; they often seemed to fall into a particular style and I felt there could have been a lot more variety. There also frequently seemed to be a disconnect between the illustrations and the text and it was sometimes hard to work out why a journal page had been selected to show a particular technique or idea.
However, many people might find her 'voice of authority' reassuring and comforting rather than invasive and irritating, as I did. If you want a book that tells you to 'buy this colour' and 'don't do that', then this would be a good book to invest in because, despite my personal reservations, there is a huge amount of good information in here. In particular, if you're new to art or art journalling and want to know about different materials and to be talked through the basics, then this book has a lot to recommend it. I just didn't like the feeling of being talked down to but I'm well aware that this may be my personal hang-up. Certainly the book gets generally positive reviews on Amazon.com and elsewhere.
I borrowed this book from the library and while I'm glad that I've read it because I did learn some interesting new stuff, I was even more glad that I hadn't bought it or added it to my Christmas list because personally I would have been disappointed. That said, I'm sure that many people would find it invaluable but I'd advise getting it from the library or checking it out in a bookshop before you buy to make sure it's right for you.