Figured I would post a simple set of rules to follow to keep your non-tank group members happy. Here goes...
Rule #1
As a tank class your number one duty is to keep the aggro off of the non-tanks. Taunt and Shout are your friend, as well as any AoE attacks. Heroic Opps are good, but useless if your party members die. If you can get a HO off, wonderfull, if not - don't waste time waiting for your HO activator, or linking abilities to pop.
Single mobs are easy to hold aggro on, it takes some SERIOUS damage/healing to pull a mob away from you if you are using taunt. Durring these encounters you have a lot more room to work on getting HOs off without jeapordizing party members.
Multi-mob encounters, however are a little different. TRY to get a AoE HO off first thing. What I do when I start the encounter is start attacking at a distance, then run to the first mob (go for priest/caster classes first) as soon as I stop moving I activate my HO, follow it up with one of the linkers, then use shout to hit each mob, doing damage and taunting each in the process. I follow it up with Assult to further damage each mob and gain more aggro. After that I use my AoE Direct Damage spell to cause even more damage/hate.
To then maintain aggro, if I can get a HO off, I start the HO - if it gets broken I still continue the same path as if it were working, finishing with Shout to again gain more aggro.
Rule #2
Keep your gear updated. Keping your gear updated means less damage or also means you have more HP. This means the healers spend less time healing you and don't run out of power as fast.
Rule #3
Make sure your group members ASSIST YOU and only YOU. A few exceptions may apply, such as if you have someone to Off Tank any accidental encounter adds. Noone should be fighting any other mob except the one you are concentrating on. If you have an off tank, he/she should be the only one that might have to switch targets. One of several situations that may call for this would be if things went bad for some strange reason and a caster was being pummeled, at this point if your Shout does not pull it back, the off tank should engage that mob and get it off of the caster. Everyone else should still be attacking your mob.
Rule #4
Be fast in multi-mob encounters, when you see the main target is about to die, switch your focus to the next target and allow the rest of the group to kill the first one. Start building aggro on the next target so everyone can assist you as soon as the previous mob dies. This keeps the fight going smooth and allows you to direct priorities durring the fight.
Rule #5
Know your abilities and/or spells. If you don't know what they do or the best time to use those abilities then you really are of no use to the group, using the wrong abilities in the wrong situation can lead to major problems. AoE attacks/spells used when a non-aggressive mob wanders through the fight will hit that mob and bring it into the fight, adding unnecessary encounters which could cause a wipe.
Those are just some basic general rules, things I have found to work best and keep me getting groups. A lot of this is common MMO gaming strategies, but you would be surprised how many people really don't know this. If you are one of those people, it's nothing to be ashamed of, it's just something you need to work on. =)