Doug Hoyte writes to say that’s he’s making his excellent book Let over Lambda available on line and as a PDF. I’ve written about the book several times most importantly here and here but you can search Irreal for “let over lambda” for the the others.
I can’t overemphasize the effect this book had on me. I learned a lot about Lisp and even programming from it. Some people complained that they didn’t like his approach to structuring his Lisp but I never had a problem with it.
The book is about Lisp Macros and the tremendous powers they provide. As an example, Hoyte gives a macro implementation of the Scheme named let construct. There are a lot more things like that in the book.
Let Over Lambda is about Common Lisp but a large portion of it applies to Elisp too. If you’d like to become really good at Elisp, Let Over Lambda is a good resource. As I said, it’s mostly about Common Lisp but a surprising amount carries over to Elisp.
In any event, you can check out the book for free and if you like what you see, you can read the entire book. It is, believe me, well worth your while.