I have designed several t-shirts that I would like to start selling and marketing to bigger vendors. What type of license, if any, would I need for that? I live in the state of Florida.
No license for State of Florida regarding such retail sales as described. You
may want to consider trademark registration to protect your design. Also,
if you sell the merchandise under a name other than your personal name,
you may consider fictitious name registration, LLC, or corporation.