What are AP points and how do I use them?

AP stands for advancement points. You earn them by winning fights, completing quests, etc.

There are a few uses for AP:
-Buying hair, eyes, eyebrows, ears, etc. from the wardrobe
-Buying extra party presets
-Buying extra design slots in the generator

There may be something else I'm forgetting... but that's the gist of it, anyways.