I have a lvl50 defense guardian, lvl 50 seer sage, lvl 50 cm commando and now working on my jedi shadow.
When I was tanking with a random group, I always tell the dps my way of doing hm fps, ie, you pull it, u tank it.
When I was healing with a random group, I also tell the dps that "u pull it, u tank it; I focus on keeping the tank and myself alive in the choas."