After you've mastered the previous five chords, here are four more to learn:

G7 0021

D7 2032

C7 3230

F  2301

With these nine chords, you'll be able to play almost any song in C or G, and you can use your capo for the other keys.

When you are tuning your bouzouki (or mandolin or 12-string guitar) with an electric tuner, you should tune each string individually while muting all of the other strings, otherwise you will confuse the tuner with sympathetic vibrations from the other strings.  Tuning your instrument carefully will really make it sing when you play.

One of the best pieces of advice I ever got was to buy a stand for your instrument and leave it out where it'll be "in your way" - you'll be much more likely to pick it up and play around with it.  Yes, keeping it in a case will protect it, but out of sight and out of mind isn't conducive to learning any instrument!  Of course if you have small children or large dogs running around, this may not be practical for you. 

 Happy strumming!