See How can you make money in World of Warcraft? Learn to trade in the Auction House. If you can buy stacks of Bronze for 2G and sell them for 3G you'll get wealthy quite quickly. Other metals, skins and other ingredients are always in demand so just watch to see what's selling. Buy when there's lots of sellers. Sell when there's fewer. Also make sure that you loot everything you kill and sell all the gray items to vendors. Most green and blue items can be sold on the Auction House for a good profit.
Make a girl character and dance in a public place either Stormwind or Orgrimmar. Some dumbass will think you're a girl and pay you.