The best place to start is by looking at what others are doing with similar products on eBay. Then make a list of what you like and what you don't like about how their shops are set up, what their policies are, etc. Then formulate your own mini operations plan.
You might also want to read the book eBay Income by Cheryl L. Russell.
Having a significant number of fans as well as positive feedback and interaction from current consumers, prospective buyers viewing social media sites can be reassured that the product or service the business provides is trustworthy.