Things your tank requests from you
I've finally gotten around to doing a dungeon in 2.0 since I've started over. I ran the dungeon about 10 times, and keep running into the same issues. So I'm here to let you know what you can do to make the tank able to do their job better.
Back line jobs, STAY BACK! Do not pull monsters and attack recklessly. It might not end badly when you're fighting something easy, but when you get to higher levels, it can be dangerous. It's a good habit to have.
Front line jobs, STAY BACK until the tank establishes hate and gets a couple hits in, then go in. Don't attack at the same time and unleash a wave of fury, then wonder why the tank can't keep the monsters off you.
There is party structure in FFXIV, it's not a free for all. I understand this may be new to some people. I almost lost my mind at a THM yesterday who decided he would be the one to pull everything, after he was repetitively asked by me and other party members to stay back.
The monsters hit only the tank, the healer only has to heal the tank, which makes their job infinitely easier and helps them conserve mp for when things get hairy.