Hey mate,
Welcome to the diving/spearfishing community! Good to meet ya.
I have never done any spearfishing in Florida, or anywhere in America.
However I can offer a few tips:
-Take it slow, rushing into this great sport and attempting things that aren't quite your level yet can get you killed. For example, diving down to depths that you aren't ready for can cause a blackout.
-Find a buddy, I recommend that you try and find a buddy straight away. Join a dive club or convince some friends to come along with you. Dive within their levels as well. I can think of nothing worse than being a buddy and watching your friend blackout deeper than you can dive, and having to explain it to their family.
-Don't get caught in the gear hype..... too much! Too many divers go diving dressed up like a Christmas tree, unnecessary items can cause drag and can ruin your dive.
-No piece of gear or fish is worth your life,pretty self-explanatory. If you're deep don't hesitate to drop your weight belt. If you get a big fish, don't be afraid to cut your float line as a last ditch effort to survive.
-Have fun!
Hope these small tips help,
Rock Shooter