When gearing up your Mage in World of Warcraft.You're going to want focus on just one thing, damage. You're going to want to smoke your enemies with your arcane wrath as fast as you can snap your fingers or do that funny looking casting animation.
Gear
While gearing up you're going to want to focus on Intellect, Spell Hit, Critical Strike Rating, and Haste.because Molten Armor gains a benefit from it and mana regen is important, but Spirit heavy items with Haste go to healers because they gain much more of a benefit from it than you do. However, don’t be adverse to Haste, just look for it on critical strike heavy pieces. You can get 4 pieces from tier 9 by grinding dungeons and find yourself at an excellent starting point. You can get the trinkets from ToC and The Frozen Halls along with some offset 219 pieces. So there isn't a lot to worry about when you first hit 80. With four pieces of 232 tier 9 gear and the rest 213s you can easily get into 10 man Icecrown or 25 man Trial of the Crusader.
Leveling Up
The Mage in Action shows what power a well geared Mage can do. No penguin can stand in your way. Old Gods, Lich Kings,and Kel'Thuzad may require additional support to kill.While leveling up you're going to want to focus on snagging gear with Intellect. Towards TBC when gear starts branching off between healing and damage you'll want to go for damage. Both sets have critical strike rating and for the most part neither bit of gear is bad unless you're running random dungeons and taking the healing specific gear from the healer. If you get any pieces of gear with gem slots then feel free to add in the superior quality Spell Power gems into them to make them beefier than ever.The caster heirlooms are by default the best ones.Dreadmist Mantle,Dreadmist Robe,Headmaster's Charge,and the Discerning Eye of the Beast are the ones you'll want as a Mage, if you have a level 80 and a lot of time to farm'em up.