Lower difficulty settings should result in you doing more damage to opponents, as a percentage of their total health, and taking less damage, so combat should be easier and faster, while requiring less tactics.
I think you will need to do a fair bit of the fortresses in order to level.
What are your stats / skills / character build?
Anyone help a newb with Warrior build ... ??? (possibly helpful if you are playing a warrior or ranger, but more focused on the early game)