Always post a buyout price on your auctions. Don't think that "They'll just bid it up anyway." Many players will not bid on an auction with no buyout price unless the item's bid price is heavily discounted to begin with. This can lead to bidding wars, but in many cases the item will sell for a fraction of what you could have gotten if you had posted a buyout price in the first place. You will have more sales at a higher price and get your money more quickly if you post a proper buyout price.
For this farm we're taking it all the way back to eastern kingdoms. We're going to be killing the purespring elementals in the purespring cavern for the item essence of water. Essence of water is a semi-rare drop that goes for a shocking 252g per piece. The caveat is that it doesn't drop all too often, but is still worth the trouble. I wasn't getting TOO many of these, but I was still making bank with them. The essences are used to create the old-world illusions, so they do have some inherent value. Simply patrol the area and kill as many elementals as your heart desires. It's a really cool and fun farm that can be done on autopilot. Usually there is noone patrolling the spot.
Repetitive daily quests are a legitimate method of generating significant cashflow. Players who spend several hours a day doing daily quests can often generate 100 per hour. Many players have funded the purchase of their elite flying mounts solely through doing daily quests. Another trick for higher level players is to do level 70 dailies as a level 75-77. If you have a hankering to get a Netherdrake, for instance, and you already have a fast flying mount (which is a pre-requisite for the drake), you will find your mid-70s an ideal time to go get that drake. Not only will the quests be a lot easier to do at level 75+, but the dailies will pay about 1200 as you level rep, and you'll get XP along the way to boot (albeit not as much as quests in Northrend.) So if you're looking for a break from the grind of leveling to 80, and want to kick back, spank some level 69s and make some decent money along the way, doing lower level dailies can be a fun way to make some extra cash.
Guide to Obtaining and Selling the WoW Token Buying and selling the WoW Token, which allows players to buy game time with gold, or make extra gold by selling the token on the Auction House. What is Blizzard (Battle.net) Balance Overview of Blizzard (Battle.net) Balance, a currency used to buy Blizzard Entertainment products including World of Warcraft character services. How to Purchase World of Warcraft Game Time The cost of a WoW game time subscription, how to acquire a subscription, gift one, and cancel it, as well as how to play WoW for free.