For this strategy to work effectively you should always create a level 1 alt or use another character on your account or another account (if available) to avoid careless spending on your main.
You should pickup enchanting as a skill just to get disenchant. As you progress through the game send all of your extra monies and gear to your auction house character and post everything that has use in the auction house for a random fair price (most green loot aren't sold in the auction house so a lot of times you will have to make the price up). 5 gold for a random weapon with good stats isn't much and neither is 2-3 gold per piece of armor if you are unable to find the item you wish to sell or a comparable one and compete with it's price.
For higher end green gear see what it would sell to a vendor for and put your auction house price 2-3x greater than that. The items with the best usable stats (stamina/intelligence gear for casters) will go the fastest but random pieces will show love too especially weapons with decent
dps for its level (regardless of stats). Try to sell an item once using the 24-hour period. If the item your selling doesn't sell then disenchant it and sell the supplies.
Now you may be thinking that you could save a lot more in auction house fees by just disenchanting your gear and selling the supplies. I have come to find that this is untrue. Even though you may end up wasting a lot of money on items that do not sell, the ones that do sell are selling for a high enough price that it by far exceeds the losses you would incur and beats out the gains you would have made by disenchanting all of these items from the start.
There are addons you can find that will help you place items in the auction house easier. Auctioneer is an example of one. It will scan the entire Auction house and then suggest prices for you to set your items at. These addons are very useful for those interested in making gold from the auction house. You can set the price and list the piece of equipment in the auction house at the same time. For example, if I have 500 silk clothes, I can set the price per stack of 20 and then list 25 stacks and it will put them all up on auction for me with one click.