Collections firms/attorneys have expertise in tracking down folks such as this. They usually charge a percentage of the amount recovered, but in my experience it is a good trade off. Unless you want to try to track these folks down by yourself, I suggest you contact your local state bar association's lawyer referral service (http://www.floridabar.org/divpgm/lronline.nsf/wreferral6?openform) and get the info on some collections firms.
In order to enforce your judgment, you can serve upon the former tenants what is referred to as discovery in aide of execution. This allows you to find out what assets they hold which you may be able to garnish or place liens upon under your judgment.
Most attorneys have services that, if you have former addresses or other information regarding your former tenants, can locate their current location. You need to schedule an appointment with an experienced collections attorney who can review your judgment, advise you regarding how to enforce it, and potentially perform the necessary execution steps for you.