Just returned from a 2 week first time driving vacation in Ireland. Some points:
1. The Garmin GPS saved our sanity as signage is not the best in Irish towns. The Garmin lady with the nice Irish accent guided us from Dublin to Galway to Dingle to Killarney to Limerick and back to Dublin with 100% accuracy. For a first time driver it was a great travel tool.
2. Hug the center line while driving. I got used to it and driving in general quickly got to feel natural. But, it is easy to drift over to your left and start rubbing your tires on curbs. I learned and kept forcing myself near the center line. It might feel intimidating at first. In towns you need to do this so you don't scrape parked cars on your left.
3. While driving you must concentrate heavily on the road. No day dreaming or talking on a phone. Keep your attention on the road and you'll not have a problem.
4. The roundabouts- thanks again to GPS. She tells you what to do and it shows on the screen. Just remember to yield to cars coming on your right.
5. With a GPS and keeping towards the center line it is, as I often heard the Irish end conversations, "...no worries then."