To quickly earn more experience for a new character, first have a character who is far along in the game but hasn't done all the palaces yet. Have this character beat a palace and go to the place to insert the gem. When you insert the gem and the experience points start to total up, pause and do the Quick Save. Then, load your new character. All of the experience points which would've gone to the character you beat the palace with will now go to your new character.