Primary farming in World of Warcraft is new to The Burning Crusade expansion. It’s a great way to make solid, steady gold to get that epic mount or new armor you might need. Obviously Throne of Elements is the best place, but it usually has a lot of others that can slow down your earnings. Scald is usually slightly better and is the best place to farm Primal Fire.
If you need Primal Manas Netherstorm is the place to go. Especially just outside of area 52. Mana rages and wyrms have good drop rates. Or the Ghosts of Mana through the ruins of the town of Kirin var. Primal Air can be found in Nagrand and Shadowmoon Valley. The mobs that drop the motes are usually quite spread out and difficult to farm.
The Nagrand Halaani Basin is one of the best places to get primeval water. Mobs are low level and easy to farm. There are plenty of them, and they’re not immune to frost, making it the perfect place for Frost mages to farm whatever primal water they need.
There is a lake on the northern edge of the Terrokar forest that has a type of Mana fish that can drop Primal Manas. This used to be a good secret spot, but these days it can have some competition.
Primal land and life must come from the gathering profession, but if your server supports it, you can farm the swamp lords north of the swamp rat outpost in zangarmarsh for primal life. And the various Earth Elementals in Nagrand for the Primordial Earth. For Primal Shadow Farming, the Void spawns in Nagrand or Hellfire.
Above all, farming Primals is a solid way to make gold. It’s easy and pointless. Try to focus on Primals with a good Auction House value on your server.