What helps me as both tank and dps, (i dont have a healer yet), is to have the target of target turned on. If i am tanking with randoms through the GF, i ask the dps to target through me, that way they dont attack anything that shouldnt be attacked. As a dps i use it to target through the tank to kill whatever he has taunted. if people havent got it turned on its really quick to do and is very helpful especially in groups where everyone is a new meet. I also find that this helps the healer as everyone is not running everywhere else.