For Single Target
You will want to reach the haste cap, which is about 700 Haste. After that, target either Mastery or Crit according to your sim.
Intellect: Your main stat, it increases Spell Power.
Haste: Makes you cast more spells in general, which means more spells during Combustion and more crits for Kindling. Also makes your Flame Patch tick faster.
Versatility: Passive damage increase while providing damage reduction.
Mastery (Mastery: Ignite): Your Ignite. Each spell you cast adds to it. Currently not so strong, but usually becomes stronger later in the expansion.
Crit: Gives your spell a chance to crit. It’s not a high priority as fire mage already has a high base crit.
The best way to calculate stat priorities for your character is to "sim" your characterFind out how to sim
The best races for a Horde fire mage are Troll and Orc.
For Alliance the Mechagnome is currently the strongest choice for Alliance Fire Mages, as it provides a passive Intellect boost.
The second choice is Dwarf as it provides a passive 2% crit damage increase.
Chest: Eternal Stats
Cloak: Soul Vitality
Bracers: Eternal Intellect
Gloves: Doesn’t affect performance, so choose whichever you prefer.
Rings: Tenet of Haste
Flask: Spectral Flask of Power
Oil: Shadowcore Oil
Chest: Heavy Desolate Armor Kit