Can i start my own plumbing business without a masters or journeymen license?

I have been doing plumbing for about 7 years and want to start doing work for myself.I want to know what options do i have.I want to put out business cards for myself.I completed the apprenticeship program for plumbing.I received a certificate from the state of Florida certifying me as a plumber.It also gave me an id number.I want to know if this certificate is enough or do i need more to start,operate and run my own business.If anyone knows please help.