If you visit just one of the sites we recommend here, make it ENERGY STAR. This is a "U.S. Environmental Protection Agency voluntary program that helps businesses and individuals save money and protect our climate through superior energy efficiency." Their website provides detailed information about improving every aspect of building and product energy performance. You can set up your own profile, use a multitude of useful calculators, search for products and vendors, learn about tax credits, home rating systems, and much, much more. You could literally get lost in this site for days, but all of it is practical advice for any size home, apartment or other building, and to fit any budget.
The Lawrence Berkeley National Lab teamed up with the Department of Energy and the Environmental Protection Agency, as well as a number of other organizations, to create the Home Energy Calculator. This is a powerful tool for analyzing you energy usage of all types and for determining where to start saving. Results are customized by location (using your zip code) and you can save your work and come back to update it later.
Since you live in Florida, this is another good place to start is you are evaluating your building and just starting down the road of energy efficiency. This site from the Florida Department of Agriculture and Consumer Services allows you to create a profile, enter data about your home and routines, and then view a list of customized recommendations. After that, you'll have a better idea of how to use the next stop, their enormous library of educational resources.
This is another good source of information, and is particularly well rounded when it comes to helping you analyze all of the different types of energy you use. This site is mostly about what is going on behind the walls, inside the appliances, and how to get the most out of every element in your home or other building. It also covers energy saving landscape advice, and is another source of good information about tax rebates and incentives.
FPL has a comprehensive web page on energy efficiency with plenty of tools for homeowners, business people, developers and other energy users. You can choose from energy saving programs and rebates, energy saving resources, and a home energy survey. If you are an FPL customer, your survey can link right into your actual billing data which makes for incredibly accurate analysis of your electricity usage.
While mostly a website about green building, look on the right side of the screen for links to some great energy usage calculators.