Find private bulk buyers, For Ex. I have one guy that specifically buys All Cata Herbs at a set price, and one guy that buys all cata ore, two different people, and it comes with time. Its nice though all I have to do is bulk mail everything to them with CoD and our set price as Negotiated, and next day ill get on and have a few lumps of gold in my mailbox. A good way to find these guys are putting a lot of stuff on the AH and wait until you notice someone buying out your auctions, then just pm them and ask if they perm buy those mats. Works for me anyways..
I sell Ores to the ppl that want ores, not that many ppl have asked for bars tho, I'm botting when im sleeping or away, and then CoD ppl the stuff i farmed. easy gold =D
If you absolutely must use the AH (which tbh I do as the muppets on my server keep wanting to re-negotiate the prices down, even when prices are stable or increasing as a market), set up two or more bank characters so that you are distribution large amounts of stock but appearing to be jsut another number in the market.