Try to master using both the Left Analog-stick and Right Analog-stick. Remember to top up your partners' items. Use lock-on targeting in all Boss fights. Do not always rely on your partners to heal you. Try to use the hit and magic attack method. For example, first lock on the target. Next, use your magic until one last MP remains then join in the pounding of the Boss. Cast magic when you regain one block of MP. Continue to pound the Boss. Remember to take care of your HP during the pounding.