Enchanting is quite different from the other tradeskills, as it is not used to create items, but to enhance other item's stats. Therefore as an enchanter, you will be selling a service to other players - namely the ability to enchant their gear so they can increase their stats.

The materials used in enchanting are the ones you get from disenchanting uncommon or superior items - this will result in dusts, essences and shards. The materials you get from disenchanting items are usually worth more than the items themselves, so you can make a decent profit from enchanting by just disenchanting items.

In The Burning Crusade enchanters also got the possibility of obtaining enchants that they can only perform on their own rings. This is a new reward for endgame enchanters, as they can increase stats beyond that of people of other professions.

Enchanting is a very expensive trade to skill up so be prepared with some deep pockets. A good way to skill up this trade is to either make a deal with a tailor friend to supply them with mats and have them create lots of uncommon items for you to disenchat or possibly decide to level Tailoring and enchanting simultanously and then disenchant all the uncommon items you produce whilst you skill up Tailoring.

The usual way to sell your service as an enchanter is by advertising your skills in the trade channel or simply keeping an eye out for people asking for specific enchants.

Tailoring is probably the best gathering trade to pair enchanting up with, as it doesn't need any gathered resources (like leatherworking needs skinnning, blacksmithing mining, jewelcrafting mining and alchemy herbalism). Also, whilst levelling Tailoring you will produce a lot of uncommon items, which you will be able to disenchant and afterwards use the results in enchanting.

Another option is to have a gathering skill together with enchanting purely for the profit.