I find the easiest and most mind numbing way is to spam devistate and occasionally throw in a revenge or heroic strike. It works for me but im intrested in hearing how other warriors do it!

A good way to make you take less damage and also control threat is as I do:

use a bloodrage before the pull, use bow/gun/throwing weapon to pull. Once the mob is at you throw in a shield slam right away. This will gain initial threat and you can now use all your mitigation skills next without losing aggro. After shield slam, use tclap, demoralizing shout and shield block. Keep shield block up the entire fight. Now you're fully mitigated, and now just use a combination of shield slam, devastate, and revenge when it's up. Also, if the mob uses a weapon, use your disarm skill. Concussive blow now and then so you stop taking some amount of damage, and a really good tactic I use on spellcasters is spell deflect. Spell deflect will make the next spell cast on you to not hit you, but the target casting it. If tclap or demoralizing shout fade from the target or targets, use it again. Just make sure you're away from all CC when you use thunder clap.

Probably one of the most effective/essential warrior skills is intervene. If a healer gets aggro, as well as a CC breaks and goes after the CC'er, target the mob, make sure you have "show target of target" on in your interface, and target the friendly player under the enemy's name plate. They won't take damage, and you charge over. As soon as you intervene taunt, stun and slam.

-Also if you don't want to lose life off of bloodrage, use berzerker rage. after a few seconds into the fight I obtain full rage and I never run out of rage through the fight, even if I use tclap, shield slam and spell deflect all at once. But then again, I have 1 point in unbridled wrath (fury) and a point in anger management (arms). Hope this helps!

I realized that being able to mitigate damage is really important for a tank ... but will demoShout really make that big of a difference when you could, instead, use an ability that builds more threat?

Well, I sometimes actually forget demor. shout until I get a few sunders and shield slams on the target. But it's still a very useful skill for mittigation, and when you get high enough level and have a decent build you can blow tons of rage without running out of it. I'm able to just keep on spamming combos of shield slam, shield block, tclap, demor. shout, devastates and everything else and I'll still have over 50 rage. If really just depends on your spec build. Demoralizing shout is probably better mittigation then tclap because tclap just slows attack speed, the mob might attack slow but that doesn't mean they can't still hit very hard. demoralizing shout will reduce the AP of the mob. You only have to use tclap and demor. shout about every 30 seconds, so you can keep those going and gather so much threat in the meantime.