Shaman PvE guide

Shamans and groups

 * Elemental and/or Enhancement shamans typically come in guns blazing at the beginning of a fight.
 * Shamans are capable healers for large groups of people taking damage in raids. This is thanks to Chain Heal. Chain Heal is extremely mana efficient, and arguably the Resto shaman's most powerful spell.
 * Shamans can make capable off-tanks at lower levels.
 * Enhancement shamans will greatly increase your group's melee DPS, because of Unleashed Rage and Windfury Totem.
 * Much like Druids, shamans should bring multiple gear sets, and use Dual Talent Specialization to quickly toggle between specs. A raid leader should not hesitate to ask a shaman with dual talents to change their role to best serve a raid.
 * If a shaman drops totems, whether in combat or just outside aggro range of the next group to kill in an instance, it's helpful to fight within the limited range of those totems rather than outside of them. They do cost mana and time, but with Call of the Elements, shamans can drop their totems fast; taking away from the frustration of tank running out of their range.
 * If you want a shaman to drop a specific totem, just ask politely. Also, Tremor Totem doesn't cancel all fears, so don't yell at us if we don't have one down.

Things Non-Shamans want Shamans to know

 * Be wary of Crowd Control when casting Chain Lightning or AoE totems.
 * Cloth wearers (Mages, Priests, and to a lesser extent Warlocks) might like a Frost Shock to get their mob's attention if they get aggro. This is especially true when Crowd Control breaks and a mob as it will run right at them when the CC wears off. Frost shock is best for this, because it is instant, doesn't have a DoT, it slows target and generates extra threat towards the higher-armour player to boot.
 * When you're in an instancing group, watch the puller's target and get ready to Wind Shear. There are times where the puller aggros a caster, who starts casting and ruining the pull.
 * When in doubt, use Grounding Totem in boss encounters.

Death Knight

 * Since Death Knights have Horn of Winter, Strength of Earth Totem is not as useful. Instead, swap out to Stoneskin or Tremor Totem. Otherwise, same totems as you would when grouped with a Rogue or Hunter.
 * If healing, you can usually ignore Death Knights with aggro due to their high armor. Just don't forget them and let them die!

Druid

 * When in a group with a restoration druid or a balance druid, the best totems to use are Wrath of Air Totem, Mana Spring Totem, and Flametongue Totem.
 * Healing druids can only lose aggro with Cower, and that stops them from healing. Help protect them from adds like any other healer.
 * Druid tanks have high armor but no block or parry. When healing one, expect a steadier stream of damage and be charging up Healing Wave instead of reacting with Healing Surge.
 * Druids gain a large amount of dodge per points of agility, so putting down your Strength of Earth totem while a druid is tanking in bear form will reduce their damage taken. Druids in cat form gain attack power from agility and strength and will also benefit from Strength of Earth.

Hunter

 * Hunters' pets greatly increase their master's damage. When healing be sure to keep a hunter's pet alive as you would any other party member.
 * Strength of Earth Totem helps hunters by increasing their attack power and critical strike chance.

Mage

 * Since mage's Arcane Brilliance and your Flametongue Totem have the same effect and do not stack, choose a different fire totem when grouped with a mage.
 * When in a group with a mage, the best totems to use are Wrath of Air Totem, Mana Spring Totem. Mana Tide Totem can help a mage's damage and mana regeneration on boss fights or difficult pulls.
 * Use Frost Shock to draw those mobs off the mage if he pulls aggro, as you will survive longer than the mage with less armour! Then let the tank pull them off of you.

Paladin

 * Since Paladin's Blessing of Wisdom and your Mana Spring Totem have the same effect and do not stack, choose a different earth totem if a paladin is buffing might.
 * If grouped with a paladin and druid, Mark of the Wild has the same affect and does not stack with Blessing of Kings. Druid should buff MoTW, Paladin should buff Might, so you should choose Healing Stream Totem or another water totem besides Mana.
 * Strength of Earth Totem and Windfury Totem are very beneficial for Retribution and Protection paladins. Spell power also helps them to a lesser extent, so Flametongue Totem is a good choice.
 * Enhancement Shamans shouldn't have mana problems with Shamanistic Rage, so ask for a Blessing of Might or Blessing of Kings. Restoration and Elemental Shamans should get Blessing of Kings and place a Mana Spring Totem, as Mana Spring and Wisdom do not stack.

Priest

 * When in a group with a priest, the best totems to use are Wrath of Air Totem, Mana Spring Totem, and Flametongue Totem. Mana Tide Totem can help a priest's damage and mana regeneration on boss fights or difficult pulls.
 * Just like with other casters, if you see a mob on a Priest, Frost Shock them to get them off!

Rogue

 * Windfury Totem is a great totem for rogues.
 * Strength of Earth Totem is good as well, because it gives them additional strength and agility.

Shaman

 * Organize with them beforehand to make sure you're not dropping the same totems they are, since most effects don't stack.
 * With 2 shamans in a group, you could have Strength of Earth and Stoneskin, Wrath of Air and Windfury Totem, Healing Spring and Mana Spring, etc. Your party will be MUCH harder to kill.

Warlock

 * When in a group with a warlock, the best totems to use are Wrath of Air Totem, and Flametongue Totem.
 * A warlock will usually use Life Tap immediately after combat to regain mana. This will cost them their health and while you do not have to worry that they are getting hit by an invisible enemy, they will be thankful if you heal them up. A Riptide is the most efficient way to deal with Life Tap.
 * If you see a mob on a Warlock (or any caster), Frost Shock will likely get them to attack you instead - better that they're attacking the Mail-user than the Cloth-user. Then find a way to get the tank's attention.
 * When healing, try to keep their pet alive as well. They are like an extra, minor party member.

Warrior

 * Strength of Earth and Windfury Totem are great for warriors as they help then give/take more damage. When you are in a group with 1 or more protection warriors, you might want to use Stoneskin Totem to reduce their damage taken.

Healers

 * The totems that most benefit healers are Wrath of Air Totem, Mana Spring Totem, Flametongue Totem and if you have them Totem of Wrath and Mana Tide Totem.
 * Healers are either Restoration shamans, Holy/Discipline priests, Holy paladins or Restoration druids.
 * Keep your eye on the healer's mana bar. If they're struggling or low on mana, throw a heal out or use Healing Stream Totem to help them out.

Elemental
As with all PvE casters, it's expected that a raiding Elemental Shaman be spell hit capped against raid bosses. With three points in Elemental Precision, Spirit can be fully substituted for Hit Rating.

Spell hit required for raid bosses: 17% (1741 hit rating at 85).

Spell hit required for raid bosses, with Draenei Heroic Presence: 16% (1639 hit rating at 85).

Enhancement
Current convention dictates that a raiding enhancement shaman needs to be spell hit capped. Therefore they require the same amount of hit as an elemental shaman for raiding. However, in addition to this, an enhancement shaman needs to consider Expertise, and unlike the elemental talent tree, enhancement has no talents to increase spell hit.

Below, there are three milestones that each enhancement shaman needs to hit to excel in a PvE raid environment. While these are in a somewhat chronological order as to when an enhancement shaman will hit each of these milestones, keep in mind that it's most effective to work on gaining hit in tandem with expertise instead of completely capping one, then the other.

First hit milestone for reaching the hit "soft-cap" for special attacks like Stormstrike and Windfury Weapon hits:

Melee hit required for raid bosses: 8% (961 hit rating at 80).

Melee hit required for raid bosses, with Dual Wield Specialization: 2% (241 hit rating at 85).

Melee hit required for raid bosses, with Dual Wield Specialization and Draenei Heroic Presence: 1% (121 hit rating at 85).

Second hit milestone for reaching the expertise cap to reduce/eliminate the chance all melee attacks are dodged from behind bosses:

Expertise required for raid bosses when attacking from behind: 26 (781 rating at 85).

Expertise required for raid bosses when attacking from behind, with Unleashed Rage: 22 (661 rating at 85).

Expertise required for raid bosses when attacking from behind, with Unleashed Rage and Axe Specialization (for Orcs using axes or fist weapons in both hands): 19 (571 rating at 85).

Third hit milestone for reaching the hit cap for spells like Earth Shock and Lightning Bolt hits:

Spell hit required for raid bosses: 17% (1741 hit rating at 85).

Spell hit required for raid bosses, with Draenei Heroic Presence: 16% (1639 hit rating at 85).

Thoughts on obtaining more hit than the spell hit cap:

Once an enhancement shaman caps their spell hit, additional hit is not nearly as useful. This is because most of a shaman's damage comes from their special melee attacks (like Stormstrike and Windfury) and their spell attacks (like Earth Shock and Lightning Bolt). It would be more important to focus on obtaining more Agility or critical strike chance to to proc more Flurry and Elemental Devastation.

Disclaimer: The above section is largely a generalization. The mechanics behind the enhancement shaman is very complex, and no single formula works for every shaman. If possible, it's recommended each shaman use simulation programs to determine with stat will give the best benefit at any given time. However, it should be considered that whichever path a shaman takes with respect to stats, in a raiding PvE environment, the above numbers (as well as satisfactory critical strike chance and attack power) will likely be expected from raid leaders looking for well-geared players who can do competitive DPS in boss encounters.