1. Dunno if it is covered in tut, but learn stair dancing, it's very important skill.
Basically, when if you take the stairs up/down, all monsters will get to attempt a hit on you, but only those right next to you will follow you.
Use this to break big group of enemies into smaller group, than heal, than go back, repeat.
Biggest killers early game to watch out for:
Sigmund (plain nasty), Orc Priests (can attack anything in LoS, they are in green, not purple), Gnolls (strong attack + swarm + often have polearms), Ogres (can 1hitKO characters), Centaurs (ranged,often good damage), bees (swarm + evasion + poison).