There are two main white mage builds I use:
First is the party support specialist. Take group heal and the charmer stance that heals resolve (can swap to heal if you know the fight doesn't deal resolve damage), and song of storms. Attributes to focus on are willpower, agility, and presence. Basically you heal up the party whenever they take health/resolve damage, and use song of storms to give a party member a huge damage upgrade. The party becomes pretty much self-sufficient, so you never have to stop and rest if you don't feel like it.
The other is the self-sufficient build. You take heal, the black mage resolve drain spell, fireball, wear a shield, and focus in agility, willpower, and whatever else you feel like for the third stat. This one you don't especially care if you party kicks the bucket, because you can deal with pretty much any fight solo. You still can support them with heal, but come what may you can handle it.