Every country is different, and sometimes even parts of countries are different. Your best to ask your local Small Business Association, or a lawyer in your location for your business.
Personally, I'd advise anyone starting ANY business to get a legal company name, and Incorporate so as to protect yourself from any lawsuits etc. There are a number of ways of doing this, but again, each country is different.
Best advise - check with your local business advisors, they're going to have the right ansers for your particular area.