Sounds like you need a bit more practice at being a Wizard. Have you spent time on Colossus Boulevard in Wizard City? It's an optional area that lets you get used to dueling two opponents at once, and will give you some more experience to level you up.
Make sure you're training with your main school of focus, and picking up any other spells from the other schools that will help you. Don't miss an assignment - check back with your teacher often!
Once you get a few more levels underneath you, you'll wonder why you ever thought those Krokotopians were a bother...
