What I did was utilize food for most combat until about the point of going into the Dragon Tower (the 1st one, not your tower). By then I was using heal pumping it up to 5 and then potions when heal wasn't good enough any more. I prefer using weapons with mana leach (learned that from DD). Also I added a bunch of skill points into mana efficiency.

Every time there I run into trouble on the road, there is always a dwarf at the bottom of it. Don't they know how to drive above ground?