As Turbo said, it's gonna be expensive, but I assure you it's gonna be worth it. First big direction, Temple Bar. Not for every day, but it's a nice place and there are loads of nice pubs. Near Hard Rock Café there's one painted in light green where they usually do live music afaik. Also, do not go into Hard Rock Café. If everything's expensive, there even more, and the staff, I'm sorry if I ofend someone from there, but they're assholes. On O'Conell street (you'll easily notice it, it has a huge spire in the middle, if you go not towards the river but towards the other end, there are also a couple of really nice pubs. Anyway, you'll find nice places all over Dublin, is a great city, you'll enjoy it. Also, if you can, I recomment checking out a hurling or gaelic football match, they're great and beeing at Croke Park is a nice thing too.