Most of Gold Guides will definitely tell you that the mage class is the best class for farming. But, it is more important to know about where to do so. The best place to obtain gold is the Terokkar Forest, specifically around the Allerian Stronghold. There are two creatures that you can attack such as the Warp Stalker and the various kinds of Basilisks. From the Warp Stalker, you can loot the Warped Flesh and sell it at 1.5 gold a piece. You can sell for 2.5 gold if you do have a cooking skill.
Do you know basilisks skill? It would allow you to take the skin off the monster, and acquire a Knothide Leather which can be sold as 2 golds .
Another place is the Outlands. The mage can also attack from far distances. In the Outlands, you can find Nagrand which is one of the best spots to farm for gold by mage class. In Nagrand, you can attack the Voidspawns. Take as much as Mote of Shadows as you can. Ten pieces of Mote of Shadows would earn you a Primal Shadow which sell for 30 gold.
With skill and practice, you can start farming with your mage at level 67. There are about 5 camps of sunfury mobs that you can kill. To start, you should try small groups for practice until you are more comfortable with the surrounding.
You should be able to kill a group of 20 and up with no problem. Even it is very boring and seems wastes time and energy, but it is still one of the fastest and most commonly used methods.
If you want to read more tips about earn gold with mage, there are several mage gold farming guides on internet, that are so much information about it, but you have to avoid some guides that involve hacking, which would cause your accounts wow be banned by administrator of world of warcraft.