This Pyramid of Conservation (developed by Minnesota Power and spotted over at TreeHugger) was designed to help homeowners prioritize steps and develop an action plan for their home. Like the food pyramid, this pyramid should be read from the bottom up. The bottom represents changes that are relatively low investment, but that help establish a good foundation and understanding in energy efficiency. The investment grows as you move up the pyramid, with window replacements and solar, energy, and wind power at the top two levels.
Visit the Pyramid of Conservation here and make sure to click on each level for more detailed information about that level's suggestions.