This is simple but you cannot protect your home as homestead if you are not living there, if it empty or if it rented out. So...just live there!
Make sure that you treat it as your home.
This means that you need to get your mail there, have your driver's license reflect that address, vote there and have power in your name.
This is important!! You can only protect 1/2 acre of land in a city or incorporated area but you can keep up to 160 acres in the county or rural areas. There is no state limit on the value of the property. There are more complicated issues if you file bankruptcy though. You can also protect your mobile home, motor home or even your boat if you live on it. If you have unimproved land though, you would still need to live on it, even if it a pop-up tent you still should be able to keep it!
Additional resources provided by the author
Article X, sec 4 of the Florida Constitution
Fl Statutes 222