Rule 1.2 - Thou shalt not kill newbie trainers, shopkeepers, or quest mobs
Getting a new player to wear equipment is hard enough, so when they actually want to go learn a spell or complete a quest and can't, it's a big problem. Most newbie teachers and quest mobs will be unkillable, but for the ones that are killable, leave them alone. Exception - you may kill fame mobs, but only once to get the fame.