Assisting is a good party mechanic.. maximise the DPS against an individual target ..

apparantly the T key targets the target of your current target.
I dare you to say that 5 times fast.

The game also has things that tanks can do, such as putting big numbers or targets over their targets head just to make it clear to people.. i am unsure if clicking on these signs targets the enemy that is "signed" or not..

You can select your tank from party list OR if he is holding aggro i guess you could target anything that is attacking the tank and press assist or T twice...