Aimed at beginners to intermediates. Uke is great for portability and basic accompaniment. More interesting is the work of James Hill who has extended the ukes virtuosity
I teach in reentrant tuning where the strings are not ordered from the lowest pitch to the highest pitch.
C6 is the standard tuning g C E A.
I don't use guitar type tunings which would be easier ( for a guitarist although guitar chords play a fourth higher ). It is the reentrant that makes the uke more interesting and true to play
In terms of size I use a concert ukulele. All other sizes except baritone are fine. The baritone uke is tuned to a non rentrant DGBE.