Let Tanks mark and pull (unless they ask someone else to mark)
DPS: once the tank has Tomahawked/Shield Lobbed the first mob, do a slow 3 count, then commence DPS. Yes, a few folks on this game use Parsers, but any content below 50 no one is really going to care. So take a slow 3 count. Give your Tank ample time to cement hate. Its not a race, well, in certain cases it is, but for trash, it doesn't hurt to wait a few before smacking it. It really doesn't. I guess I have been lucky, since starting a tank, I have only had a few bad experiences, but the best experience I can give new tanks is this: speak up! Immediately let the group know that you are new to tanking, or new to tanking the dungeon. Most people will be understanding of this and not go crazy. But if you just run away and start pulling packs, everyone will assume you know what you are doing and follow suit. Don't be shy/embarrassed to profess your newness, everyone has to learn at some point, right? But don't wait to tell people until after you have wiped several times to the first boss. Same goes for heals, if you are new, speak up! I promise you this: after waiting 40 mins to an hour for a dungeon, the two DPS aren't going anywhere. this game hates new players it seems, which would explain why people are afraid to say anything. Yes, you will encounter jerks, but they are the minority. Suck it up, if they don't like it, they are free to drop and wait another hour for a group. This goes both ways though; don't assume you can be a jerky tank, because if you leave, someone can always just change to tank, queue up in DF for already in progress, and come back into the dungeon and finish it for the people you left. Respect and kindness win the day. A lot of good people play this game. Don't get discouraged after a bad experience, learn from it, and keep moving. We need more tanks!