Fretboard Roadmaps is kind of a pedagogical mess. Still, it has the information, pictures--a motivated beginner could use it. I am a guitar player; it seems like the kind of thing a guitar player thinks a ukulele player would know. Movable chords, movable scales, intro to chord melody, a dictionary of "fancy chords". My issue with it is that it is rather generic (does Fred Sokolow even really play the uke?). When to use chords is a matter of style. It's hard to tell a beginner why to use a sixth chord.
I came to the uke as a guitarist, but still found I had to actively learn the fretboard and where to play chords. The way I did it was by intervals.
The 3rd, 2nd, and 1st strings are: C E A
The fifth fret notes are up the interval of a fourth: F A D
The seventh fret notes are up the interval of a fifth: G B E
The different CAGED type barre chords can then be associated with those notes. Once you are solid on these notes/chords, you can fill in the blanks for the rest.
My fingers didn't fit for chords above the seventh fret on my soprano, and my KoAloha only has 12 frets. I am not really wild on chords above the fourth position or so. I don't think they sound very good.