Listen to Irish accents. Look on YouTube and watch movies and interviews for good examples of what you're trying to emulate. However, beware of impersonators out there -- and there are plenty.
Brad Pitt, Richard Gere, and Tom Cruise are not good examples. Stick to true native speakers; RTÉ is a safe place to start. It is important to note that the northern counties have a quite different accent [look up the Ulster dialect].