Holding Threat

[Nehru]

As all the posts say before me, marking is you friend as a tank.
/mk attack1 <t>
/ac "Shield Lob"
That should help some. When people aoe, I use a healthy mix of flash and tab target combos.

[Runalong]

In my experience if DPS don't want to follow markings or give you time to get threat then that's their problem not yours. Just make sure you're got enough threat on the mob so that when the dps tanking it dies it doesn't go for the healer.

Hopefully SE will implement a blacklisting system so you don't end up being grouped with undesirables in future.