There Will Be Profit

Title
If you haven't experienced the film yet, There Will Be Blood, directed by Paul Thomas Anderson is the blog title's inspiration. I had seen it for maybe the fourth time on HBO while I was initially delving into the Auction House and the theme fit so well. There is a scene where the protagonist, an oil man, explains very dramatically and viscerally, that he will utilize someone elses commodity to make his money - by drilling diagonally for oil into another property.



This notion of capitalizing on the resources and ignorance of your neighbor is the very essence of being a WoW profiteer or goblin. Why spend your primary resource - time - doing dailies or farming mats when there is a population of thousands already doing it for you? When you can capitalize on their shortsightedness, mistakes and laziness, you allow yourself the biggest profit of all. More time.

Add-ons
There have been countless others that have explained their AH User Interface far better than I could, so I'll just point out the benefits I find most helpful or unique.

Postal - Make sure to customize options on what to open. I choose to exclude mail with item attachments so I can safely Open All and only fill up my bag space with gold and items I know I will be re-listing immediately. The 12-stacks of items that were mailed between characters can then be distributed, returned like a ping-pong ball to save on bank space or opened at your leisure once all important mail has been taken care of.

Auctioneer Suite - I really only use Snatch and Disenchant features under the Search tab. I have combined the themes of Snatch and Vendor to look for profit a step further than most do. While the Vendor feature just looks for items below a vendor's buyback price, you can add anything to Snatch with a threshold you set.
Let's take Dark Jade for an example. If we merely used Vendor, we'd only see these as profit if they sold for less than 25 silver each. However, if we take into account that any cut version vendors for 50 silver (100% markup!) and any Perfect cut sells for 1 gold(400%), then we can include it and any other green quality gems into Snatch for a threshold greater than 25 silver and still make money.
We can then apply this to any simple-crafted item(single reagents) for quick crafting profit that you can schedule in bulk and do while scanning the AH or marketing yourself in trade to save on time. Forest Emeralds are 3 gold, but cut they are worth 4 gold 50 silver.
This all assumes you have a crafter in the respective profession and an excess of stock that allows you to liquidate through a vendor while still having enough to meet the demand for crafted items that use these resources.
Make sure you update your price thresholds on everything often enough to not miss out on market fluctuations or get burnt by a tanking item that you continue to buy in bulk.

Quick Auctions 2 and LilSparky's Workshop - These are most valuable to me because of their ability to save the crafting queue by account, not character. I can do a summary on each of my posting toons that sells in a certain group, glyphs for example, and my lvl80 scribe retains the QA2 crafting queue for all of them.
I find using Groups is essential for effortless posting and canceling. While it can take a significant amount of time to setup, it becomes priceless in the long run. Just like with Snatch though, update your settings whenever the market changes so you don't miss out on trends.
I set up multiple Groups for my glyphs so each posting toon can have their own unique schedule, fallback, undercut amount, etc. This helps to distinguish them as seemingly different sellers and makes it harder for others to effectively shut down my slice of the market.
I have Groups for: enchant scrolls at or below 200g, 500g and 1000g values, dusts, greater and lesser essences, small and large shards, each Northrend Darkmoon Card variety, vendor pets, each color of cut and uncut gems at green and blue quality levels (epic gems listed individually to maximize current market value), Snowfall Ink, all other inks, Runescrolls/Armor/Weapon Vellums, etc. Basically each category of items that you want to share a certain value and item-per-post amount.