We have not gone on our trip to Ireland yet but I have some advice to pass on. For those of you who have not booked your own Bed and Breakfast before let me share some insight.
PLEASE do not be afraid to book direct. In fact I encourage booking direct either via a phone call or emailing the B&B directly. RS also shares the same view. I usually start with an email and then phone the B&B directly to give them Credit Card information. For the most part everyone is a joy to talk to and sometimes we end up chatting for a bit.
I have noticed that some of the B&Bs (even when you go directly to their website) have an online booking form. This is a bit odd because when I have looked at the price online it has in some cases been higher than when I contact them directly. Not always but in some cases.
Trip Advisor is a good place to start. You can view photos from travelers and read what they have to say. I must laugh at some of the things people complain about but I guess some folks are hard to please.
One last thing and I think this is very important. If you do an online booking or book through a 3rd party DO confirm with the B&B. One of the B&Bs we booked at had the "online booking" form even though we went directly to their website. As I was reviewing the email I noticed that it was a request for a reservation. It stated that if we had not heard from the B&B in 48 hours to contact them directly. Well, it had been over 48 hours so I called and left a message and also emailed them. I finally received an email back from the B&B accepting the reservation.
Okay, maybe this is the last comment :) DO, DO, DO re confirm your reservations. We are 3 months out from our trip and for those couple of reservations I made using the online booking form (this is a form that is the same on several of the sites so I am assuming it is a 3rd party booking the B&B uses) I am going to keep calling or emailing until I feel I have reached a real person. One month out from our trip I am going to personally make contact again and reconfirm with all 13 B&Bs. That way they know I am coming and I know they still have a room for me.