Many people find that vacation in Ireland to refreshing and reinvigorating. However, during certain months, the weather can be rainy, cloudy and cold, even during summer. So check the weather forecast for coming months, before even planning to go to Ireland. Even if the weather is expected to be warm, you should bring along some protective and warm clothing. If you plan to visit upscale restaurants, make sure you have formal wear.
Many tourists prefer to rent small cars and take care to have a parking disc on hand. Local customs demand that visitors confirm accommodation in bed & breakfast by evening and breakfast is usually served early.
During a travel you should only take bottled water and also avoid eating fruits that have been washed using tap water, locals are already resistant to germs in their native environment, but probably not you.