One addition to other good posts here is the need to keep the lowest cost items on the AH. You won't sell much if other goblins are constantly posting the same items at prices lower than your own. At least on my low pop server, this is a big issue. We have numerous goblins and camp and repost at lower price. TSM makes reposting easier, but plan on needing to repost on low pop servers to get sales over the goblins.