Bouzoukis fall into two categories, Greek and Irish. Another way of looking at it is bouzoukis and citterns. The traditional Greek bouzouki is usually found as a four course, bowl back instrument tuned CGFAD, on ewhole tone lower than the guitar. The more traditional three coure bouzouki is tuned the ever-familiar DAD. This is the sort that I play and have used on my CDs. Irish bouzoukis or citterns come in quite a few variants, usually four or five courses with a muititude of tunings usualy based on fourths and fifths.
A mandolin is tuned to the same octave as a the violin. Bouzoukis are all in the guitar range and lower. The three course bouzouki that I play is tuned exactly like a standard bowed dulcimer. There is always some carry-over from one stringed instrument to another, but there is always somthing new to learn as well. Bouzoukis and bowed dulcimers go very well together. they do compliment one another.
Playing by ear is always helpful. The complete musician should be equally comfortable doing it either by ear or by paper. Makes for a more harmonious outcome. I'll be including more ear stuff in all my upcoming workshops.