Saving money on energy costs during the winter starts with good insulation. Adding weather-stripping to doors, installing double-pane windows, and using insulating foam between walls are all great ways to lower your energy bill. And while some energy-saving tips, like installing double-pane windows, require a significant upfront investment, one of the best energy-saving tips is also the cheapest: put on an extra layer or two. Wearing a sweater around the house instead of a t-shirt will allow you to set your thermostat a little lower, which can make a huge difference in your energy bill over the course of the winter.