First, you should check the zoning on whatever piece of land that you purchase. The reasoning behind this is that some land can't be built on.
Next, I would check if there is an association. This could add to your costs as well. Poinciana has one of the largest associations in Florida. http://www.polk-county.com/cities/poinciana/
If you haven't contacted a local agent, it would be in your best interest to have them provide you a CMA for land or a few similar pieces of land prior to investing.
My plan is to buy them and wait for them to appreciate (hopefully within my life time), so in theory, there should be no tax consequence until I sell as I do not plan to deduct any of the expenses associated with it until I sell the property.