Open Question: Do I need to file forms to have a entrepeuner business?

I want to start a business and I want to be an entrepeuner. I do not want to be a partnership nor a LLC at the moment because I am running the business and nobody else is involved. I was thinking about switching over to a LLC if it becomes bigger. My business is a service (graphic design/advertise/writing/editing) That is what Im skilled/talented/majored at. My question is at the moment, do I need to file forms to have a entrepeuner business? How do I start it? How do I register it? How would I file taxes? How would I make sure it is legal so I do not get in trouble? I need some business help/advice and information Please and thank you