it? Some vendors have a minimum amount you HAVE to spend with them to even place the order at all. Meaning, you have to spend at least $500 up front (or whatever their minimum is). It's important to know if you have to meet the minimum every time you order with them or if it's just a first time order thing. Order minimums can be annoying because most times you won't find multiple items that you want from just one vendor.
their products based on how soon they're available to get shipped out. You need to make a game plan to decide what season your shopping for and how soon you are looking to get your inventory shipped to you. It's always smart to shop a season or two ahead but if you're wanting a few items to ship to you ASAP for launch, etc you need to make sure that the item you pick is available to ship right then.
packed? Almost every item besides shoes and accessories come in packs of 2,2,2 or 3,2,1. You'll have a better feel for what sizes you run out of the fastest and who your customers are down the road but for now, just get in the habit of asking.