I kept Yukari on heal/support pretty much the entire game. Aside from that, as AndrewB said "Knock Down" is a good one... boss battles are best played by ear... expect to take a few cheap deaths from bosses as you're trying to figure out their weaknesses (or use a guide, I guess ;P)... umm aside from that, save often, don't be afraid to rest when your fatigued, as you level and get further in the game it'll take your party longer to wear out, so while it may seem like they get tired fast early on, that won't be much of an issue down the road.
Try to maximize one girl's social link before moving on to another otherwise you might have to deal with jealousy and reversed social links which wastes time you could be spending leveling them higher (though Maya -- the Hermit -- doesn't count as a normal social link so you can spend time with her as much as you want), and if you find you have nothing to do at nights (not usually an issue first time through as you can always study), you can raise your persona's stats at the mall arcade (make sure to equip the one who's stats you want to raise).
Hmm.. what else.... oh best way to get the treasure mobs before they ran off and disappeared, I found, was using a bow and standing up on the elevated ledges in the corner rooms and firing as they were down below. Or slowly sneaking up from behind and shooting from max distance (though often they'd run as soon as I fired so your milage may vary). Make sure to check Elizabeth's quests every so often as there are many that have a limited time to complete (usually by the next full moon).
I think that's enough rambling for now ;) Best of luck with it! I'm super excited for Persona 3 Portable myself :D
Posted 2 weeks ago