How should I start an online store?

I would like to start an web-based store to sell audio equipment. I generally know what I want to sell and what engine I would like to use to sell it (Goodsie seems like a good option). It’s important to become an authorized dealer for the products I sell, what should I do to make sure I am accepted when applying? What is the best way to build inventory and how much inventory should I keep? I don’t have cash-on-hand to build a significant inventory, what is the best way to go about getting a bank loan and make the right moves to become successful?