I second Gained JP Up for every character. That ability is great.

I would also recommend learning Accumulate or some other ability that you can do with no nearby enemy (I don't know what it's named in the remake, but it boosts a character's own strength). This allows you to gain JP for all characters even in the first couple of moves where you may not be able to do anything else.

Also, if I remember correctly, the monsters you encounter randomly on the world map level up with Ramza (the story battles are all static-leveled), which means it may be a good idea on a first playthrough not to let Ramza get too far ahead of everyone else in your party.