I'm only starting out, but to make some quick cash, I sell drops on the AH. Grain seeds sell particularly well. Being a THF, I can pretty easily steal willow fishing rods; I sell those too. Then, like other's have said, saving random stuff until I get a stack of 12 and selling. I don't know if this applies to other places, but in Bastok AH, a single zinc ore sells for more than a stack of pickaxes; quite profitable. After all of this, I feel like the richest newb in the world.