I hope this basic guide helps make everyone's group experiences more successful and enjoyable.
GENERAL GUIDELINES FOR GROUPING:

1.If you don't know the dungeon you're running, ask. People are usually happy to explain the mechanics of the fight, but if you don't say anything, die to something you shouldn't, and cause the group to wipe, you will annoy everyone. Avoid death and annoyance; speak up!
2.Rely on yourself before your group. Eat food before the run begins so your health and primary stat are as high as they can be. Have potions ready and actually use them when you need them!
3.SYNERGIZE! There are very, very few abilities in the game that have a synergy option that sucks. Plus, if you have Undaunted passives, you will get resources back for activating it (on top of the extra damage or resources you're gaining from the synergy itself). Synergies are basically free DPS that restore resources -- take advantage of them!

DPS GUIDELINES:
1.Resurrect your allies. If someone dies, the tank and/or the healer are busy keeping the rest of you alive; it's your job to resurrect the fallen ally. Immediately.
2.Help your healer: Use roll dodge, block, and generally move your feet when necessary. It's easy to get absorbed in your DPS cycle, but sometimes you need to block a heavy attack, roll to avoid a spell, or stop standing in fire. Don't assume your healer will keep you alive if you don't do anything to help him.
3.Kill adds first. DPS players love to show off their single-target DPS against bosses, but the fact of the matter is, those archers in the background will kill your group faster than the boss will. There are some fights where you can ignore the adds, and your group will tell you which those are if you're new, but the general rule is burn the adds before you start on the boss.

HEALER GUIDELINES:
1.Be proactive, not reactive. Being strictly reactive will get people killed. Before fights start, put a healing-over-time (HoT) on everyone and refresh it throughout the fight. Throw out bubbles while the boss is casting his big spell rather than waiting for it to finish. Don't wait until people are almost dead to start doing what you're there to do.
2.Have a few support abilities slotted. When you're not healing, tossing out a stun, buff, or a synergy option is very helpful. Luminous Shards, Bone Surge, or Mystic Orb (from the Undaunted line) provide group members with excellent synergy options to regain resources and add some extra DPS at the same time.
3.If you are not a Templar, tell your group that they need to stack. Every class can heal, but not every class can do it quite as easily as Templars. Everyone else relies primarily on Combat Prayer or Healing Springs to keep people alive, and both of these spells require the user to know where everyone is. Tell your group to stack so you don't have to waste precious time looking for them.

TANK GUIDELINES:
1.Taunt effectively. Over-taunting is a thing. Wait at least 5 seconds before taunting the same target or it will become immune to taunting and attack whoever it wants. In trash pulls, make sure you're taunting as many targets as you can, not just the biggest.
2.BASH! This is a basic game mechanic that is overlooked far too often. When there are little red lines going into a mob, that means you can bash (light attack while holding block) that mob and stop his casting. This is extremely effective against healers, archers, and even some particularly powerful boss effects. USE IT!
3.Be a leader. The tank is the defacto leader of the group, as he has to initiate every fight and be the first to take every corner and run into every dark room. Tell your group how and where you tank certain bosses if it's different than the norm and make sure people are ready and know what they're doing before major encounters.