No book that I know of?
That saying: " A picture is worth a thousand words " is very true with guitar wiring.
The problem isn't so much the difficulty in wiring, but the multitude of different ways to wire a guitar, the different switches used, and potential modifications you can do to tone shape. From a treble bleed for the volume, to a capacitor inline with a bassy pickup, there are hundreds of different ways to wire a guitar.
And all of this goes out the window when you get a 5-way super switch. Perhaps the most difficult switch to wrap your head around and integrate your ideas onto.
As to best practices, well there isn't really any. There are at least 2 ways you can wire even the most basic of guitars and each way will have a tonal outcome. The question is what is your desired outcome? You may have heard the term 50's, or modern wiring as it refers to a Les Paul, both work and one is brighter and clearer than the other.
I have not heard of or seen any book that explains all the electrical theory, best practices, and wiring ideas. And if there is one, it will have diagrams. Diagrams are probably the best way to wrap your head around it. Once you can remember a diagram without referencing it, then you can begin to open your mind to other options and ideas without having to do major research on how to implement them.
