Well look around you and see who has plenty of signs in your area, you also should call out at least 3 agents to give you an idea of pricing and their fees. Agree it in writing. Normally it's a percentage plus costs such as Daft/Myhome etc.
As Bronte says check the signs in your local area & these days most viewings are for groups of interested parties so it might be a good idea to go & view another house for sale & you can see how the estate agent operates, often choosing an estate agent is based on their personality, how they deal with prospective buyers is very important.
Dealt with a cheaper less known e/a and regretted it.My advice go with the Sherry Fitz however,short-list 3-4 company's invite them round to do a free valuation and go with your instinct or who you feel will go the extra mile for you.
I dunno if you watched Desperate House Buys on RTE the other night. There was a house in, as far as I recall, Clonsilla (D15, right?).
Anyway, the asking price was the 200k mark, and it sold for around 300k. That's about 50% above the asking price.
It's on the RTE player.
I dunno if they mentioned the EA, but a 50% increase sounds like they know how to sell and get you a good price.
I dunno what the procedure is for using multiple EAs, but I assume you only pay the one that actually gets the sale. But I might be wrong on that. http://www.rte.ie/player/ie/show/10285050/