My thought on EXP gain are as follows:
Basal EXP per day: 1-3. Everybody (only for really boring days.)
EXP from training MG powers: 5-10. Everybody
EXP per kill: Varies. Story and up (They get event EXP for "facing the legions of Hell" or some-such instead.)
EXP for plot events: Grows as involvement increases. Everybody, but higher Affinities grow
much faster
EXP for defeating antagonist: 50-500. Depends on who it is and how hard they hit
EXP from funky dreams: 0-50. Epic and up
EXP for major accomplishments: Lots, whatever you consider lots to be. Everybody.
Meeting New Magical Girls: 5-250.
Probably everybody, but possibly just Divinity (Goddess Grey and Red gave 250 EXP, Goddess White gave 5. Clearly it's inversely dependent on how nice they are. Since the Maidens of the apocalypse also gave 5 EXP they must be very kind.)
Optimal growth rate would thus be to first train and introduce yourself for a bit, then tag along with more powerful people to do important things. I wonder how many novices Red Rose has taught how to be a Magical Girl by now, and how many of them are still around.
