New guy

Hello! I decided to join this forum to take my own routine up a notch but also to get some advice about becoming a trainer. I live in South Beach so there is a lot of business as well as a lot of competition, I'm sure. I have never been a trainer but I have had trainers on and off for half my life. I want to know, is it better to get a certification (and if so which ones?) or try and get a job at a gym? Ideally I would like to be independent and make my own hours but then how do I use a gym? I know a lot of places won't let you use their gym to train even with a membership.
Thanks in advance for any advice!
-Jared