I think every landlord needs to have a copy of Chapter 83 of the Florida Statutes. You can run a google search and read through the statute. Make sure you have a copy of the lease, your 3-day notice, and all communications between you and the tenant. If your previous tenant has not objected to your intent to retain the security deposit then you are entitled to keep it. You can pursue legal action for the remainder of the damages with the court in your jurisdiction. The clerk of court in your county may have some more information on their website.
The Florida Department of Consumer Affairs has a wonderful brochure with useful information. http://www.800helpfla.com/landlord_text.html