Hmmm. Don't fight the Boss Bat, the Goblin King, or any other high-end bosses when you first get the opportunity. You'll want to make sure you've gained a few levels since taking the quest before fighting them - they're mad tough. Overlevelling in this game is your friend.

Also, you can find some pretty decent stuff in the Flea Market for sometimes good prices.

Other than that... hm... don't get discouraged. A mysticality class is, I believe, one of the hardest to beat the game with, right up there with Accordian Thief. Just make sure to boost your stats as much as possible. Oh, and fuse the batskin belt with the dragonbone belt buckle when you can.