Most Irish musicians use either GDAD or ADAD(low to high). Both tunings make it quite easy to play in the key of D; the first also allows for some easy chords in G, the second works better for A, but will give you a less full sound when playing in G.

   A mandolin-like tuning, GDAE, but one octave lower, is also used, but requires long stretches for some chords, so it is most useful for either a short-scale instrument or a player with big hands. Most of these short-scale bouzoukis, especially if they use this mandolin-like tuning, are said to be octave-mandolas.

   Most well-known bouzouki players, like Donal Lunny and Andy Irvine, use the GDAD tuning. The 3-course Greek bouzouki, not common in Irish music, is used by Alec Finn of De Dannan fame. He uses the traditional Greek tuning for this instrument, which works well for Irish music - DAD. All chords given for GDAD tuning work for this tuning also.

  Tuning:  There are many methods for tuning Irish bouzoukis, depending on what the player is intending to do with it. I shall extend the range of string choices, as I try them out, but it really depends how you tune it, so you may be involved in buying individual strings.

*GDad is ideal for tunes in the key of G (E, B and C with capo) Typically the tuning used by Donal Lunny and Andy Irvine, the disadvantage is fingering changes from the mandolin on the top string.

*GDAE like mandolin, but long stretch for some chords if you are going to use it as a rhythm accompaniment. I play one tuned like this, with octave pairs, for tunes and simple chords.

ADad is good for tunes in D and A (E, F and F#  with capo) Again, you need to learn a whole new set of fingerings if you are a mandolin/violin player.

GDgd open tuning, simpler fingering for chords.

FCgd F tuning, used with capo 2 as octave mandola ADad

Plus the Greek practice of using octave pairs on the lower two courses is possible, but this will cause problem for chords higher up the neck as they will sound out of tune. If octave pairs ARE used, for mandolin style playing, then the lower octave string traditionally goes on the low side of the pair, the opposite of the 12 string guitar octave strings, which are on the high side of the pair.

(Note: Roundback Greek bouzoukis have a much longer scale length, and are usually tuned to CFAD. They can't be tuned with Irish bouzouki strings or you cpould seriously damage the instrument.)

  The Irish Bouzouki Chord Chart.

There is a lot more info on Han's Bouzouki site on the links page.

 As I play Bouzouki tuned like this, here are some simple chords, courtesy of Han.

DAD traditional Greek bouzouki 3 course tuning (many of these can be found with 8 tuners for the simple reason, mandolin tuners were easy to get hold of, so 2 tuners were often not used.)

CFAD traditional Greek bouzouki 4 course tuning

DGBE modern Greek bouzouki 4 course tuning (in fact guitar tuning)

http://chordlist.brian-amberg.de/en/bouzouki/standard/