My recent aha moment came when I opened up the section called "Position Seven." I had already figured out that playing ukulele is essentially the same as playing the high four strings of a guitar with a capo on fret 5. Position seven on guitar is thus equivalent to position two on ukulele, with a more limited range (from G on the staff through D above the staff). Perfect. I started playing the exercises for position 7 on ukulele and am having a blast.
I'm looking forward to transferring this knowledge back to guitar.