It sounds to me that the paint was put on when there was too much moisture in the wood. That's probably a big problem in SW Florida. The most important part is to make sure that the prep work is done right. You'll want to scrape any loose, flaking paint then sand the edges. One product that I've found particularly useful with flaking paint is Peel Bond. Brush it on, it will go on milky and dry clear. Peel Bond is amazing for filling in unevenness caused from scraping and wear. Plus it gives you an excellent surface to paint over since it is also a primer. One last bit of advice is to not paint your home in direct sun if possible because paint can dry too quickly in the heat, which can also cause problems.