Yeah, Gain JP Up is virtually essential, you don't ever really equip anything else until the end of the game, or if you are having a lot of trouble with a battle.

Save before ever random battle, you never know what the luck of the draw will be. Some times you get a super hard encounter and lose a character and have to reload.

I always try to make sure I take at least one character who can heal/revive into every battle, because things can go bad.

And enjoy! Welcome to the greatest gaming experience this planet has to offer.