for the most part, i let DPS attack what they want unless i am marking mobs. if i am, i will not be building threat on any other mob and will not pull the mob back until they realize what they are doing wrong. (healer is always excluded from this, unless they are dpsing as well)

and i don't let dps pull. ever. they get one warning when they try the first time, and if they pull again i sit down and let them die.