Compost, compost, compost, Terese. Most counties in Florida have a composting program, so contact your County landfill. Ours gives it away free, but you have to load and haul it yourself. It's the best possible amendment for our sandy soil.
Anything you buy from a nursery as 'topsoil' will be that compost with sand added, so not as good a value. Be careful if you get any kind of manure that it has been composted a bit, too. It can burn your plants if it's too 'hot' or fresh.
Again, don't amend the soil in by the house. You want that soil to drain and dry out as fast as possible when the heavy summer rains are upon us, c/w high humidity.
