Fire mage greatest strength lies in its high burst, high crit spells, with instant pyroblast procs the amount of damage done is on top of the charts with good RNG.

Rotation for Fire Mage Wotlk

Fire Mage Priorities

Living Bomb (Keep debuff up) > Scorch (Keep debuff up) > Frostfire Bolt (early-game) | Fireball (end-game) > Pyroblast on [Hot Streak] procs

Tips

For AOE use Living Bomb, Flamestrike and Blizzard.

Scorch debuff is not needed if there is a warlock in the party or raid.

Use Fireblast or a [Hot Streak] Pyroblast procc in movement.

At the end of a cast, an instant spell can be cast without occurring GCD, this is true for every cast/instant sequence, should be used to maximize DPS.

Use cooldowns when there is barely any movement or crowd control effects to maximize DPS, best way to do this is by knowing the fights.