Grouping tips for all Warriors

• Piercing Howl (Fury Talent Shout) helps chase down runners and is worth investing in (as well as extremely helpful in PvP).
• Shouts do not break Polymorph (commonly known as 'Sheep') or Sap. Thunder Clap will.
• Be wary of using Intimidating Shout in an instance – it rarely helps due to the fact that it's a Fear-type effect. Intimidating Shout is particularly dangerous as it affects up to 5 nearby enemies, not just one, like the Warlock AOE Fear. It can be used in situations where all enemies have been cleared out in a large area, so that you don't have to worry about adds. Also, the enemy you have targetted when you use this skill will not be feared, but frozen in place. In a close fight where there's just one enemy left but your party needs a few moments to bandage and get enough mana for another spell, this can buy you the time you need. And in instances such as the beginning of Shattered Halls, Intimidating Shout can be very helpful.
• Hand over any mana potions and mana drinks you loot to those who need them, especially your healer.
• A full Rage bar grants no additional bonuses. Should your Rage bar become full, you still have plenty of available attacks, and you should use them as soon as possible. If the main tank starts raging up past 40'ish it's probably time to ragedump by spamming Heroic Strike with the sunders and Slam (see here).
• All warriors should have a good shield and good one-hand tank weapon. Carry them with you at all times, they don't do you any good when they're in the bank. Being ready to off-tank will make you far more popular in groups, particularly raids if you carry a tanking set of armour. Level 70 DPS warriors should consider investing in Felsteel armour as it's easy to buy and a good entry-level tanking set.
• Use Battle Shout and Commanding Shout effectively. If your group is taking heavy damage, then Commanding Shout may provide enough additional health to keep them standing (Over 1000 hp without talent points). If you have a large number of melee players then consider Battle Shout for the attack power bonus. In groups where there are multiple warriors, co-ordinate before you begin, as you need to avoid using the same shouts.
• Demoralizing Shout generates threat, so DPS warriors must wait until the tank has sufficient aggro before using this.
• If your main-tank dies towards the end of a boss-fight, it is often critical that you step in and take over tanking. Although you will not last very long, with a good healer you may buy enough time for the other DPS players to finish killing the boss. This is more commonly successful in non-heroic encounters or when a boss is at very low health.