I will be travelling to Ireland for the first time for 4 days. Any suggestions on what is a must to see? I will be renting a car so I can go anywhere.

Sorry, no one could possibly help you based on your question. When are you going? What airport are you flying in to? What do you want to see/what are your interests? Have you driven on the left before? Are you going solo?

All those questions . . . Plus: do you actually have 4 days (not counting your arrival and departure days); Do you have a specific reason for choosing Ireland (ancestors, history, scenery, whatever)

Four days is not much time to see Ireland. I would just stay in Dublin or Galway and do some day tours from there. You can take the go bus direct from the airport to Galway. Great tours from both cities and you will see more with a guide for first short trip. If you insist on driving then I would head to Belfast and the north coast. Back to Dublin area and seeing the city and Glendalough/Wicklow area. So much to see and all very good so you can't really go wrong.

I am flying into Dublin. My daughter is going to school in Carlow and I am visiting her. We are renting a car and she is going to try and take me to a few places. Thank you for responding

How many full days do you have? 4 days means 5 nights. That will determine how far you can go. Carlow is south of Dublin - about 2 hours from DUB. Driving on your arrival day is not recommended (assuming you are flying in transatlantic)

I will be arriving at 5:30 am on Friday and leaving Monday night to go to Scotland for a few days. It is a very condensed trip and that is why I was hoping to see the highlights in a short period of time. I will be arriving from Toronto Canada

It isn't that long of a ride. You don't have more than a 6.5-hour flight. Get some shut-eye on the plane. If you are not comfortable there is the train from Heuston station. I would see Wicklow and Glendalough, That is a beautiful area. Cashel is not that far and Kilkenny. Congrats to your daughter sounds like you will be back to visit.

Thanks for the heads up. I was thinking of doing those spots once we arrived making our way down to Carlow. I just need it to stop snowing! I am leaving snow and was hoping for a bit warmer weather.
I am renting a car, is it difficult learning to drive on the opposite side of the road?

If you if you are renting an automatic, driving will be a lot easier. I only drove there once, as DH is our driver and I am the navigator. For the first day you just have to keep thing “left, left, left.” Where people seem to have problems is those pesky roundabouts and while exiting parking lots. If you get the car at the airport, you will run into your first roundabout right away.

If you take the motorway you may pass through an electronic toll. Check with your rental agency ahead of time, because you may have to pay this yourself, either on line or at designated shops.

I am renting an automatic and I am used to roundabouts. We have quite a few of them.
Is it worth renting a GPS with the car or are the road signs pretty good. I have a map and a navigator

If your navigator has a cell phone with google maps, that’s all you need. We had gps one time (we didn’t ask for or pay for it, it just came with the car) and never used it. But, we don’t mind getting a little lost, can be fun. The major roads are well marked, it’s more the secondary roads that can get you lost.

Great!
Thanks so much for all your help!
I can't wait to go!!