Here's a tip to get some easy exp.
- Find an area with monsters that are appropriate for your level.
(i.e. at level 20 don't go to 1st floor World Tree)
- Go to an inn and recruit filling up your party:
--- If you are a Priest, recruit a Mage and 2 melee users.
--- If you are a Mage, recruit a Priest and 2 melee.
--- If you are any Melee, recruit 1 Priest 1 Mage and another melee.
The priest will keep healing you throughout the battles and the mage provides distance support. This is a quick way to get exp since the battles are fast and can keep on going. Also if you run out of TP just use normal attacks until you get your desired TP amount.
Complete the game once to be able to start a new game with your current stats and items.