If you can drive in Chicago, then you’ve already got some seriously key skills! :)
Traffic will be less heavy in Ireland, but there is that “other side of the road thing.”. It doesn’t take that much to get used to being on the left side of the road, and oncoming traffic being on your right, while steering from the right-hand side of the vehicle. Depending on the make of your rental car, the turn signal might be on the left or right side of the steering column. We’ve had the wipers come on sometimes, while trying to signal a turn!
One important thing is to stay centered in your lane - not too far right or left. The passenger should be active the whole time, assisting the driver. If you’re doing all the driving and she’s doing all the navigating, she should frequently remind you not to go too far to the left (away from oncoming traffic but close to the left edge of the road), as well as the speed limit. Remember that will be in kilometers per hour.
Gas and brake pedals will still be on the right and left, like you’re used to at home. One of the toughest things might be remembering which side of the car to get into, if you’re driving!