Pretty much what ChriZirhC said is how it goes for brd. Unless you are in a static group, when and how you use songs will always differ and this isn't taking into account any random deaths that can change up what you use also.

Song usage is something you begin to get a feel for on the fly. Have a melee heavy group? Probably might need Paeon here and there. Mage heavy group? Use Foe when you can. Always keep an eye on healer/tank MP and use Ballad wisely - EI: Use in spurts here and there, or use in chunk with BV then switch over to Foe or Paeon as needed/able. All anyone can do is give you an idea to base usage on, the rest is up to you and the group you're in.