My advice is research. Never jump in. Look at location (if a store), pricing, marketing, and product. Figure those things out first before moving forward at all.
I work in cigars (so it will be my example), so naturally I have to figure out that arena. Then I have to figure out what kind of cigar I want, and find a factory and blender to get me test smokes. Then I have to look at that blend, the tobaccos, and cost. Aside from that, have to design and make bands, boxes and so on. Plus I have to get licenses to make tobacco products (since I am selling to the public) and have a wholesaler and retailer license. I of course need a merchant account if I am accepting credit cards (whether in store or online), and I have to have certain legal aspects to cover my ass (you have to be of legal age, smoking causes cancer, and so on). Of course, setting up federal and state forms to show I have a new business. With all of that, figure out costs and how to do it.