I'm playing yet another warrior alt and doing instances with it. (I've got a warrior fetish, leave me alone.) Its very different than tanking instances on a geared warrior, you have to be a lot more careful for one thing.

With Naissa I can get away with being a bit lazy and don't have to do things perfectly. Nothing is going to insta-gib her. Even if I wasn't playing an undergeared tank alt, it would probably be a good idea to get back into the habit of doing things properly now that we're so close to the expansion.

1) Remember that you're only 1/5 of an instance group. Your role is extremely important, but there are 4 other people with you. Your role is to protect those people, even if its from themselves and their own stupidity. You're the poor sap that stands there on the front lines and gets smashed in the face repeatedly so that the other people don't have to. Keep your Taunt and Intervene bound to easily reachable keys. It could be the difference between life and death for someone in your group. Don't assume that someone can handle something if they pull it off of you. Unless you don't like them, then by all means, let them die.

2) Speaking of hotkeys - Remember to bind all of your abilities to keys. Even if you're a PRO Clicker, clicking for intervene is probably going to result in someone dying.

3) Be familiar with, at the very least, the boss fights of the instance you're doing. I've gone into a few instances blind and relied on the DPS who had been there before telling me what the bosses do. Usually this resulted in them leaving out something that the boss did only to the tank. Thats not a good situation to be in. (Not as bad as a 3 melee DPS heroic Mech group that doesn't know how the Positive/Negative debuff works and commits mass suicide because of it.)

4) Never give up. Oh no, the hunter, while trying to trap, just pulled an extra group of mobs and now they're headed straight for you? Don't give up! Try your best to get the mobs on you and keep them there. Do your best to stay alive and keep everyone else alive. I've been in some situations that seemed hopeless, but by not giving up, we were able to get through them with all or most of us alive.

5) Save as many people as you can. You're a warrior, and lets face it, you weren't given many ways to get AWAY from combat. You're big and slow, and if it goes pear shaped you're going to die. You don't have feign death, invisiblity, vanish, etc. So when things go bad, and you KNOW you aren't going to pull through...Try to save as many other people from dying as possible. Give the mage the time for invisbility to work, or if people are running for the instance entrance (Which is annoying btw) - Try to buy them time. You won't make it, but they might. You're going to eat the repair bill either way.

6) Don't be afraid to tell someone what to do. You're the tank, which means that you're usually the group leader. You assign CC, mark mobs, etc. If someone isn't doing their job, don't be afraid to point it out. It could very well be the difference between success and failure. If someone is doing a horrible job of .. whatever their job is. Feel free to offer them tips, just don't be a braying jackass about it. Nobody likes that. If they act like a giant stupidhead after you were trying to be helpful in a friendly manner, THEN its time for braying jackass mode. (Is that a druid form?!)

7) It may seem tedious, but keep Commanding Shout, Demoralizing Shout, and Thunderclap up at all times. Demo Shout and Thunderclap make a huge difference to the damage you take. Make your life and your healer's life as easy as possible.

Don't break the CC with your thunderclap. This can be hard when someone sheeps a mob right next to you, but adjust your position so that thunderclap won't hit it.

9) If CC is getting broken early by someone and its not getting applied again, or if your mage just has a huge blonde moment and doesn't re-sheep...Just grab the mob. Better its beating on you than running around wildly beating on your squishies.

10) They ARE your squishies. The other members of your group are a lot more squishy than you. Its your job to protect them. I'd say to think of them like your children, but some people have psychotic hatreds of children, and besides that a child can take a beating. I mean...Umm...Disregard that! >.> They're more like...eggs! One hit, they're gone. So its really important than you don't let that big orc over there with the massive axe come over and whack Legololz, Shanku, Darkflame (The frost mage), or Charles (The healer, they have the most normal names...usually) in the face. Its not pretty. Here is a picture to help with that thought.

11) Don't pull a Naissa and charge head on into a massive group of mobs with no CC markers...Unless you're with friends. And have gear. Gear is always good for that.

12) This one goes for healers too. Realize that you're going to get blamed for things, even if its not your fault. You can do your job perfectly, but all it takes is for ONE loud mouth jackass to die and suddenly you're being called the worst Tank/Healer ever, told that suicide is your only option, that you're horrible, the honor of your parents will be called into question, etc. Don't listen to these things, they don't actually mean anything. Don't feel sad and emo if someone tells you that you're a bad tank/healer. Just add their name to your "List of people to try my flamethrower on."

13) Don't end a Tips list with 13. Its unlucky.

Hope this was helpful, but if not - I'm pretty doped up on NyQuil at the moment. Woo sickness gogo!

PS - I'm guildless on the armory, this is accurate.
PPS - http://forums.worldofwarcraft.com/thread.html?topicId=10697504509&sid=1&pageNo=1 - Found this on the forums this morning. Good times.

Disclaimer: I do NOT beat my own children, I don't even have children. Nor do I beat anybody else's children, even though I'd sometimes like to. >.> That part of Tip #10 was just a joke!