in the golden pages there is a list of RIAI listed architects in your area. try any of these.
also, talking to friends/colleagues about experiences they have had is very useful.
have a look in magazines such as Architecture Ireland, House, you'll find a good selection in good bookshops and newsagents. see if you like any of the houses featured and make contact with these architects.
also, look up their websites to see if what they do interests you.
above all, make sure you pick an architectural practice that you can get on with, go in and meet them, see what their design philosophy is like.