Book or website about book design
Well I thinks is time to answer this question properly instead of create a large chain of comments. In fact I'll recycle few of them here.
First of all, TeX (and LaTeX in some way) is the translation of the lead technology used since the mythical Gutenberg to the digital age. So, TeX has a lot, hundreds of commands that let you control with great precision where the printer should put the ink and with which form.
Unfortunately although TeX gives great power and control over the page, does not teach you how to design and use all that power correctly and wisely. There is the need to learn some graphic design and typography focused on book design, which is what interests you learn. If you are not pursuing a professional career in design, then you have to learn on your own (like me) what is perhaps somewhat unorthodox.
As I said before, the book design is a very exciting topic. But you should take care about two things the language, and the book culture in your country. That's important because many decisions about design in books depend to some extent on the local or national publishing tradition.
I can suggest a whole library of books on design and typography books, however I'll try to focus on what may be helpful as a beginner.
Basic Books
These give you a general introduction, without being exhaustive give you an overview to help you understand what all this.
- Modern Book Design by Ruari McLean. Is not my favourite, it was a little bit boring for me (was not my first), but is good.
- Adrian Frutiger is one of the most important typographers of the 20th century (and one of my favourites). He has many interesting books about typography, the most of then I read are published in Spanish by Gustavo Gili Publisher, in English the only one I've found is Signs and Symbols: Their Design and Meaning by Adrian Frutiger.
- Type and Typography by Phil Baines and Andrew Haslam also can be useful for you. It brings you an enjoyable overview.
- Once you have a better idea about what is behind the desing of a book, you can learn a little bit more with this one: Designing with Type by James Craig it's basic, good and very enjoyable too.
- The typographic world can be fascinating but when you are newbie is not easy to think with types. Then Thinking with Type by Ellen Lupton would be perhaps the best choice.
Specialized Books
Now that you know of typefaces, font families, compositions, and so it's time to learn how to use all that. As your aim is design books, you'll need to learn how to create visual structures and use grids.
- A good start point for this would be Grid Systems: Principles of Organizing Type by Kimberly Elam.
- Making and Breaking the Grid by Timothy Samara. He has also another nice book for design that you should read later: Design Elements: A Graphic Style Manual.
- I can't close this section without suggests the books of Edward Tufte, perhaps the most famous: The Visual Display of Quantitative Information.
Books about books
Finally the last suggestions:
- This one was a before and after for me about the design of a book and also one of the most cited books about desing: The Elements of Typographic Style by Robert Bringhurs.
- A more technical book about the design of books Book Design by the same Andrew Haslam, a famous designer which makes paper engineering for his books.
- The Chicago Manual of Style, perhaps is not a book for learn to desing a book, but is very useful for write books and has a lot of suggestions you can use for improve your designs, specially in English language.
Well, surely there are hundreds or maybe thousands of other books that fall outside this brief list. It was not my intention to make an exhaustive list of course, but to make very specific suggestions on my experience might be of use.
About the websites, I'm afraid that I know of none that can help you, and the only one I could recommend you for visit is in Spanish.
Finally I hope these tips are useful for anyone who wants to delve into the design behind LaTeX classes and understand the reasons behind are based certain decisions and design conventions inherent to all of them.