Fire Mage
Rotation
Opener: Scorch to 5 stacks of Fire Vulnerability, Fireball, Fire Blast on cooldown.
Priority: Keep 5 Scorch stacks up, Fireball as the filler, Fire Blast when moving, Flamestrike or Blast Wave on packs. Ignite rolls with crits, so crit gear first.
Cooldowns: Combustion on the pull or when Ignite is rolling; Blast Wave to peel; Cold Snap is Frost's.
Forever notes: Molten Core and Onyxia punish Fire; Forever's first raids (Barrow Deeps, Hyjal Summit) have no such blanket immunity, so Fire is the Phase 1 raid spec.
Stats
Spell Hit to 16%, Fire spell power, Spell Crit (Ignite is 40% of every crit), Intellect, then mp5.
Crit is king for Fire; past the hit cap it is the stat to chase.
Numbers for every spec and a gear comparer: stat weights.
Where it ranks
See the tier lists for PvE and PvP placement, and Classic vs Forever changes for what Blizzard altered in this class.
Wowhead and Icy Veins keep spec guides of their own: Icy Veins Fire Mage, Wowhead class guides. Our rotation notes are editorial, written for the Nov 2 tuning.