Okay, i really wasn't sure where this belonged, or even if its been posted before (ran a fast search, but due to the vague nature of this, nothing really came up)
some may see it as common sense, but others will likely not have seen it before.
so here we go.
STEP ONE Take whatever you wish to sell (For example, a stack of buff food) and split it in half.
Send half to your alt.
STEP TWO Post your auction up on your Main for a fair bit more than you actually want for it (so using the example of the buff food, post for about 60g)
STEP THREE Log your alt and post your auction at the price you ACTUALLY want (so 45g for the Buff food example
It'll sell as people with auctioneer see it as under 100%, and some will buy to use, others will think they can profit.
This works better on a slightly more obscure item, i use it once i've farmed some enchant recipies/ companions.
It will also only work if your auctions are the only ones up there, so try posting them up on wednesdays, as this is when the AH is generally quietest.
THE RUNDOWN:
1: split total goods to sell in half
2: Post half on your main for high amount
3: Log alt and post up other half for real price
4: Wait
5: Profit
hope this helps a few of you. good luck, have fun!