Planning a trip to ireland

May I suggest that you begin by doing some basic research - pick up a few guide books (starting with the RS guide), read and compare their offerings, then rough out an itinerary that reflects your particular interests, accounts for your available time, etc.
Then maybe come back here for specific advice to specific questions that you may have.

I prefer the west coast of Ireland. The best part are the small towns and the people you meet and can chat with in the pubs. The problem with planning sightseeing at places such as the Ring of Kerry, Cliffs of Moher, Dingle peninsula etc. is the threat of bad weather, rain, fog, low clouds. Last wek in Kerry you couldn't see 100 feet because of the dense fog. I have spent 21 days there over three trips and the sun has been out for a total of 8 hours.

To really see all of Ireland, you need to rent a car. Land and do Dublin first. Then rent a car and go outward and onward. Read guide books as already suggested to get an idea of what you want and how long to spend at each stop. Check Airbnb, hotels, BnB's, hostels for rates and availability. At times, you can stay at one place and go out and back each day. Saves packing and unpacking and if you got a good rate for staying a week, even better. We enjoyed Waterford, Youngal (pronounced yall), Cork, Doolin, to name a few.

When are you going? How much time do you have? Are you planning on renting a car or using public transportation?
What are your interests?( culture, pubs, architecture, outdoors etc)

We’ve been on a guided tour to Ireland in August 2015 with my wife and 2 children so I can give you some ideas. The must-see places are Dublin, Ennis and Waterford. To me, the most impressive sights were at the Dingle Peninsula and at the Ring of Kerry. These are paradise-like spots! They combine pristine nature and beauty frozen in time. We succeeded to be at both places at dusk and this is the best time of the day to enjoy these places.

I think your question could be answered better if you can provide a little more information. When are you going to Ireland? How long will you be there? Will you be renting a car? What are your interests: nature, history, music, etc.? With only the information you gave, the only suggestion I would make is to avoid overloading yourself with too many places to visit. In my opinion, you will get more out of a trip to a foreign country if you go for quality over quantity.