Here is a link to help you out.
For S Florida, I would encourage you to get two kites, a light wind and a high/moderate wind kite as those are the two predominant weather patterns we get here (15-20 mph and 22-30 mph, usually due to cold fronts).http://jimbodouglass.blogspot.com/2011/ ... lator.html
I have generally found the chart to hold true. One catch is that as wind goes down, the larger kites also assume you step up to a larger board and that is not evident on on the kite size chart. As a beginner, buy the lightwind board first and the moderate/high wind board last of all gear purchases as the lightwind board will be easier to learn on even in stronger winds when you are first starting out.
Definitely get lessons through at least the waterstart stage and make sure you go over safety and upwind body dragging. Dont try to shotgun this as you can and will get hurt.
Im a big fan of starting with a trainer kite to get body dragging down, then doing a few lessons for safety, setup, and waterstarts, then practicing on your own until you can ride upwind. The FL kiting season is about to end as is true for much of the USA, so there will be huge discounts on gear shortly. Most schools will give you the gear you need for lessons so you may wish to hold off buying gear for now until you get thru the lessons and we start the next season.