I am going through Matt Kloskowski's "Layers" reference book. I looked at it back when my Photoshop learning curve was still pretty steep. I'd grasped enough of the basics of working with layers that I set the book aside after glancing through it and grabbing a couple of nifty tricks.
I'm now going through it, chapter by chapter, lesson by lesson and I'm picking up a whole lot more nifty tricks as well as sorting out some techniques that were a bit blurry in my brain. Some of the things that Matt teaches are things that I don't do. For instance, I don't group my layers. I'll link them, but I don't group them. I usually don't name them, either.
Naming and grouping are techniques that I file away under a 'best practices' heading. If I were doing work that others would see, and perhaps even edit, I'd name and probably group my layers.
Matt also lives and dies by keyboard shortcuts. I'll admit, knowing a few of these is going to be very helpful, but I don't like to put down my pen to tap on the keyboard. It becomes a pause in my work flow to use a keyboard shortcut. And learning too many keyboard shortcuts at once is confusing.
Simply performing the exercises is not enough to really learn the things that Matt teaches in his book. The exercises are excellent, the directions are detailed without being confusing, and I understand what I have just done. But for the information to really sink in, I've got to use it in my own work. I go through a chapter then I work on my own projects, using some of what I've learned. Then I go through another chapter.