Assembly (ASM) Hacking Book

When I start to read this, what area(s) should I primarily focus on, so my brain doesn't explode?

Well first you must know what is a stack, an accumulator or a register so I would start by chapter 2. Then you can jump on the commands (opcode) in chapter 4 or before you can check how the arithmetic opration are done in assembly (chapter 3).Then would come the adressing technique in chapter 5.

You don't have to read everything, in fact I haven't read much of this book, I prefer working with subroutines in the game dissasemblies and trying to understand what they do with a list of opcodes (commands). But I guess it takes longer that way than if I would have read the book.