Create a web site with shopping cart. (Find the site that gives you the best deal based on what and how much you are going to sell.) If possible consider using a drop ship company so you do not have to invest in stock and you do not have to maintain your inventory or house it. Then use the best SEO practices that you can afford to get on the top of ever search engine. Further you will want to use social media such at facebook, pintrest and twitter to name a few to build a following for your business.