How to Easily Level Your Mage to 80
Leveling a mage is pretty easy. As a ranged caster, you're not supposed to take any damage in most situations, and you have several ways to keep mobs off of you. Additionally, there are no mandatory mage quests in the game anymore. Unlike, for example, warlocks who must obtain their pets through quests, mages have it easy and can just train most spells from any mage class trainer. Finally, a mage relies heavily on his or her spells for damage, not that much on gear.
Sure, gear will always make a difference, but leveling in green and blue quest rewards should be fine. If you got heirloom items and enchants, or gold to buy bind-on-equip blues and epics from the AH, all the better. But don't make the mistake of thinking you must have best-in-slot gear at every (or any) level while leveling. Going out of your way to get a few more points of intellect or stamina will only slow you down.
To summarize, if you have a higher level toon on the server, do supply your new mage with powerful gear. If not, just go with what you can get.