The best way to run your business from the facts that you have written seems to be to set up a limited liabilty company or a sub-chapter S corporation in your state of residence and have customers contact you to do business through your presumed website and other forms of advertising.Upon receipt of the orders, you simply ship the items to your customers where they desire the shipment to go. To register your entity as an out of state entity in each of the fifty (50) states in this country will be expensive.I suggest that you follow up with a consultation with a business attorney concerning your business venture and how best to establish it with the least amount of liability exposure.