Well, most of my posts have just been about stuff I have been doing. This one is a bit different. This one is about multi-target tanking as a warrior.
Multi target tanking for a warrior is generally much more difficult than the other tanking classes (especially paladins). I'm going to go over a few things that can be a big help when trying to tank more than one mob.
1) Thunderclap. Thunderclap is the first ability I like to use when multiple mobs are on me. This gives good initial aggro and gets those targets beating on you. Thunderclap only affects up to 4 targets, so it is certainly no consecrate.
2) Demoralizing shout. Using Demo shout will give you a bit more aggro and also make the mobs perhaps hit a little less hard if they do escape.
3) Once you have done these, go with your standard rotation on the main target (when you can). You should also be tab devastating is there is more than one extra mob. With enough mobs beating on you, rage should not be an issue. You cleave very liberally. I would use it as much as possible.
4) If you are still having difficulties, dress to impress. It may not be the best looking thing, but the Rep shield from the Sporeggar is a very good trash shield. Out fit it with a shield spike and get to work. You can also have someone make you some storm chops, which do damage when you are struck.
All of this can make your multi mob tanking that much easier. If you have any questions, you can ask me. Tankingtips.com and Tankspot are also phenomenal resources for tanks at any stage of your careers.