HELP!! Starting a small business in Tennessee

Hello! Hopefully someone can give me some good direction to go in! I am currently selling fishing lures on a website.(Bayou Bug Custom Jigs - Home) I registered with Rutherford County, Tn under Sole Proprietorship. According to Rutherford County, if I make $3,000 or less annually I do not have to register the business with the state. But then some places say you have to go through the dept. of revenue with the state no matter how much you do.



So basically what I am asking is, what is my next step that I take after I have registered with Rutherford County under Sole Proprietorship?