I'm a DPS player who is relatively new the game and this thread has been helpful and informative for me. Thanks to the people who took time to explain it.
I do have two questions about what has been said here.
1. If an enemy switches to targeting me instead of the tank, is that my first clue that I was doing too much damage? Or are there earlier hints? Is there a way for a skilled DPS player to make sure they don't pull threat while still dealing an optimal amount of damage?
2. I understand from reading this thread that if I pull threat as a DPS player I should stop attacking. What should I do while I'm waiting? Attack something else, or stop attacking entirely?
It depends - if it's a non-elite, the tank is likely not focusing on it in favor of trying to keep aggro from an elite.
For the most part, just kill it. If it's an elite or higher and is charging you or your healer, I will usually try to root/slow it so the tank doesn't have to chase it down and CC if I can, again so the tank doesn't have to run it down.
Nice part about being extreme-range DPS is that you can get a very good view of the fight and kind of see what needs to be done.