From My Basic Solar Advice:
First, reduce your load. Insulate, caulk, seal everything you can. Weatherize everything up the wazoo, even going so far as to get a blower door test - pressurizing your house with a large fan installed in the front door and having a professional go around finding where all the air leaks are. Get the most efficient appliances (refrigerators tend to be the largest electrical load in the house) and lights that you can find and afford and install them. When you've become as efficient and energy-conserving as you can be, then start thinking about solar.
Then, and only then, go solar.
Updated
Simple Solar - Part 1: Solar Cookers Simple Solar - Part 2: Parabolic Concentrators Simple Solar - Part 3: Windowbox Air Heater