Things we request from our tanks:

Mark targets. We can't hit what the tank refuses to establish, and the casters can't sleep or repose which you keep hitting to try to "build aggro." Flash works on slept targets, but so does healing aggro, so maintain Flash and don't break my sleeps!

Don't pretend you're the boss of the dungeon. 5:8 runs I've done with pugged tanks they didn't know their hand from their arse, and they needed their hand held through the content just as much as new DPS.

If the healer says "stop," STOP. Your survival depends on the healer's state to protect you. You rush in when they are trying to cast Protect/Proshell or put Stoneskin on you, you're gonna suffer. That causes more healing, and thus more healing aggro YOU have to deal with. You are one part of a team, you are not ALL of the team with some NPCs along to damage/heal for you.