Honestly, Fireball/Ice Spear/Thunder isn't as hard to train as some of the other more annoying skills (such as Meteor Strike, Snapcast, and Spellwalk), but if you ever suffer from extremely high CP while training those skills, well...
http://wiki.mabinogiworld.com/view/Kitchen_Dungeon
Hope you like playing with eggs, spice, fruit, water, and the like, because they're going to be your best friend for a very long time.