The GLFS book is designed to be taken in optional chunks and cover most setups users might be using. It is different from both LFS and BLFS in that LFS is meant to be followed almost command by command unless otherwise told so, and BLFS has packages scattered throughout in chapters, only certain ones meant to be followed through, such as Xorg .
Please read Which sections of the book? for more information regarding that. Along with that, please read most of this section carefully as it explains important conventions to help you if you were to get lost or stuck.