lol, i remember playing it...
recommended class: mage.
avoid (unless looking for hard mode): warrior.
recommended early skills: heal, replenish mana (can't remember actual name). Upgrade throughout.
recommended powerfull skills: shadow, and the three-shot skill.
When stuck, use the training room. Bring a shield, even though it'll get destroyed in one hit-it's one less hit you actually take.
bonuses: one guy gives you a ring. To activate, look at the moon, you'll get a bonus skill point.
also, for emergency funding, there is a guy with leaves, take leaves to someone upstairs, bring medicine back, sell each for 3 gold.
To cheat, save, go into the monster portal (or the human portal) on a level with a reward, get killed, restart, defeat training ward: you just got the item anyways. (really nice for levels with multiple possible rewards)