I had people telling me to do the 4 mob scenario above. But I was always lost and had no idea where we were going. Sometimes they would skip stuff. I have no idea what to skip or in what order or when to shoot gun vs charge. And I'd charge and I could hit one ability and then I was out of rage. If I switched to defensive I'd have nothing left and spend awhile just swinging.
The only thing I've seen work is regular old Taunt. And it only works for a bit.
I have a few tips for you:
Taunt temporarily puts you at the top of the threat meters but you have to follow up with another ability to stay there. Usually I use sunder or revenge.
Have the dps wait a few seconds before starting. At least get 1 sunder on the mob. If you don't start with aggro and the mobs go after people in the beginning the entire pull is a shitshow as you won't have enough rage.
Have the most competent dps be a main assist if possible. Sometimes they assist the tank and you're tab targeting sundering/revenge multiple targets and they think they're supposed to switch but mostly they shouldn't.
Aoe threat generation sucks. Cc and burn down mobs.
Know the ways to pull: charging in, shooting, or body pulling. Body pulling means sneaking close enough to the mob that is sees you and attacks. Unlike shooting or charging, the mob didn't take damage, so its "cry for help" radius is a little smaller. This means body pulling can sometimes get fewer mobs.
Use corners to bring back caster mobs, who will stop casting and chase you once line of sight is broken. Tell the group to wait and you'll bring the mobs back. Even if you have to run a bit it's alright. Activate blood rage while running back, stand right around a corner so all the mobs will gather at that point.
Always keep an eye on patrols. When you get an opening to pull them on their own, take it.
I tell the Healer to say mana when theyre low because I'm managing the mobs, setting the pace, pulling, etc. and sometimes I forget to check your bar.
DPS warriors are idiots, and most of them remember a well geared arms warrior in pvp being ass ponied by healers being an unstoppable freight train (this is true). Or that fury warriors are the best dps in raids thanks to endless theory crafting in private servers, and they want to be big dick dps. The real truth is that 50% will burn out on warrior, 30% will find their dps/pvp role, 10% will actually be good at it...and the last 10% will actually tank. And only half of the tanks are going to be any good, and fewer will be amazing.
Tanks are the rarest party member and in the biggest demand. I'm level 41 and I don't group with dps warriors in the group unless they don't need the drop I want. Yes, you can make demands as a tank. Don't like it? Feel free to stand around for another 45 minutes hoping another warrior will tank Stratholme for you; I've got an another group that sent me a tell and needs mw for something. I'm not saying be a dick about it, but I have lost 6 out of 7 rolls to DPS warriors in SM and I'm done with that shit already.
While leveling try to do quests and grind mobs equal or lower level than you. Higher level mobs will dodge, block, and parry more often, and it's rarely worth the time and frustration to solo grind orange mobs/quests.
Most importantly: become an alcoholic. Many DPS could level to 60 without knowing the difference between their ass and a hole in the ground. You have to know your job well and basically be a tour guide that gets constantly punched in the face for a bunch of ungrateful mongoloids that can't even make a macro that says /assist Kharzette. This will make you bitter, so keep the booze handy.