Sole proprietorship is a good choice for people just starting up a business because it does not have a lot of costs or legal requirements to set up.
As a sole proprietor, you should register your business. Business Licensing differs from state to state. If you are doing business under a name other than your own legal name, you need to get a business certificate or register as a DBA (Doing Business As). This allows your customers, your suppliers, the government, and anyone else your business deals with to know who the real owner of the business is.
A DBA can help you open a business bank account and may reassure some clients that you have lasting power. In most cases, you register for a business certificate at the county clerk's office. In a few cases you register with the state or city. You can call the county clerk to find out.