Just to further confuse things, I've heard the 'Octave Mandolin' referred to as an 'Irish Bouzouki'. W/t tuning the same as a mandolin an octave lower. Regardless, once one can play one they all become accessible as the chord forms are the same. Same w/a tenor banjo.

The 'Greek Bouzouki' has a tuning like the top 4 strings of a twelve string: D-G-B-E w/the D&G having octave strings and the B&E tuned the same. So, one would approach it from the perspective of the top four strings of a six-string guitar. Using the same chord forms and scales.

What Nashville studio players have been doing the last few years is adding a couple of tuners to the headstock and re-configuring the nuts and bridges of inexpensive, vintage F-hole guitars and turning them into Mandocellos for a different rhythm sound. Keith Urban uses this trick alot. One has to listen close.