People are very friendly and don't mind giving you directions if you ask. Renting a car may only be worth the expense if you plan on driving across country, and even that may not be worth while as busses and trains are much less expensive and quite comfortable. If you do choose to drive keep in mind that many Irish roads are very narrow and courtesy is a must. In general drivers are used to give and take in these situation, and at times innovative to say the least. They are giving you the right of way.
Public transportation is very convienient and affordable.
City busses cover wide areas and in Cork, for instance, bus fare is only 70 pence per person. Busses run frequently, beginning at 7 am until 11 pm, and bus stops are numerous. You can call a taxi to pick you up where ever you are or catch one in town. Fares are reasonable and taxi drivers are very helpful, good guides for the most part and do not try to take advantage of you and your lack of knowledge of the area. Some taxi's do charge a small extra fee for baggage or extra passengers but it is not at all unreasonable.