As we all know, there is an Auction House in WoW. It is the best place to make money. It is also where some of the dummies ruin it for the rest of us. I am going to go over a few helpful tips to help you not be one of these dummies.
Install Auctioneer: Seriously. There is not reason not to have this. Ever. Auctioneer is probably the single best addon for manipulating the AH. It practically does all of the work for you.
The first thing you will need to do after installation is scan. The scan take all of the prices of all of the items on the AH and saves them. You will want to do this at least once a day and preferably twice a day for the first week. This will help weed out the harmful for noob auctions such as the spring water that was 1000 gold for 2 days and then 50 gold after that. That is not a deal. That is people messing with your scans.
The easiest way to scan with the new version of auctioneer is the little blue fast forward button on top of the AH screen. You used to have to type /aadvgetall. Now you just click the pretty blue button. And click it again when it says to click it again.
Look for Deals: There are many different kinds of deals you can look for. There are several Auctioneer options where you can set parameters for what you are looking for. You can set up a snatch, which will buy the item you specify at or below the prices you specify automatically. You can also search for items that will sell for a profit to the vendor. Yes, there are some dummies that put items up for less than the vendor price.
If you are low on cash, I would recommend looking at the safe bets. Usually in the form of herbs and ore. Auctioneer will give you a percentage. This percentage is the percent of the actual market price the item is going for. You want to look mainly at blue percentages which means someone put it up for less that 50 percent of market price. Buy these items and resell them.
Post Your Auctions: Dont be "that guy". You are trying to maximize your profit. If you see that there are several stacks of saronite ore on the AH for 20 gold a stack, dont post your 20 stacks at 10 gold a stack. Sure you will sell, but the dummies will come out of the woodword. You flooded the market with low price materials which causes the other impatient people to undercut you. Before you know it, Saronite is going for 5 gold a stack and you have lost a money making possibility.
Only post a few of each thing at a time to avoid flooding the market. If the prices are way down, hold onto it for a bit. If there are only a few at the ridiculous low price, buy them out and repost them at your price. Notice I said a few. This leads me to my next bullet.
Avoid Trying to Create a Monopoly: It is OK to find you nich market. There are little markets out there that can make you a nice chunk of gold with little competition. Dont try to monopolize any large markets. You will only get burned. A market is usually large for a reason. There is profit to be had. Say you want to corner a part of the enchanting market and buy out all of the high level dust. You buy out all of the dust and repost it for 4 times the market amount. The smart businessmen undercut you by half. They know one of two things will happen. People will buy at their price first, or you will buy at their price to hold your monopoly. Your items will not sell and you will be broke.
Remember, despite this being a Blizzard game, Zerging does not work when it comes to AH effectiveness.