I usually check the current prices just before I put it up, lowball it and make SURE you put in a buyout price. Most people that are grinding want the stuff they need now, not in 8+ hours. Seems to work for me. Also, if you have time, offer the in the trade channel on the way to the AH... might not need to make the trip at all. Also, get ot know your guild.... trading for stuff you want is often much better then the actual coin.