To locate somebody in Ireland, the first thing to do is have the name and surname of the person ready; from there, the first option is to go to Census Finder, which can search for persons in the Republic of Ireland and Northern Ireland. If the county or town that the person lives in is known, the search for the person should be much easier.
Once the town or county of the person is found, it is possible to use sites specifically designed for Ireland, such as 118.ie, which allows you to search and identify all of the people with the same name in a specific area and gives access to their contact details, such as address, phone number or email.
The person that is being searched for may not be in the directories for a specific town, so to improve the chances of finding that person, search a larger town in the area or a neighboring town to find people with that name. If the specific person cannot be found, a good plan of action is to contact others with the same last name of that person in hopes that they may be relatives and have the person's contact information.