Driving in Ireland - Tips and Feelings

Tips about Ireland highway:
For most of the highways, they are for free. For some of them, there is a toll.
For M50 between Dublin airport and Dublin center, you need to pay a toll fee online.
Tips about driving on the left:
On the highway, stay on the left and overtake others from the right.
On the highway, the exits are on your left.
When you turn left, make a small circle and look at your right.
When you turn right, make a big circle and look at both sides.
To enter a roundabout, look at your right and go left.