I've heard sage described as the job that would come about if someone went "What if white mage were a shield healer?"

Though, I don't precisely agree with it - sage is about having tons of CDs and knowing how to best rotate/pace them. Like Scholar, it lacks the brute force of cure 2/benefic 2 for when the CDs are out and healing might get a bit rough.

For starting out healing, I'd stick to white mage. Exceptions might apply if you have extensive experience healing other MMOs, or perhaps you're the type of person that likes jumping right into complex, "sink or swim" jobs. (And healing really is sink or swim - where the whole party will often wipe with you, outside of boss fights)