During the winter your goal is not to keep the heat out, it is to keep the heat in (and the cold out). Make sure there aren’t any bubbles or cracks in the sealants surrounding your windows. Cold air is more insidious than hot air and will find a way in if you leave any gaps or holes in the exterior of your home. You should also check out any weather stripping to make sure that it is in perfect shape.
In addition to the blinds that you’ve got in place to keep people from being able to see into your home, you should consider hanging curtains to help absorb heat and keep it from passing through the windows. Putting a layer of thick plastic over your windows (between the panes and your blinds or shades is also very helpful in stopping the heat from leeching out through the glass.
If you can afford to do so, it is worth putting in “weather proof” and double paned windows. These help regulate the temperature of your home (which helps reduce your heating and cooling costs) and can be used to give your family a break at tax time.
The windows are the eyes to your house. You know how to keep them safe and how to dress them up. Using them to help you maintain a comfortable living environment is also important. Use these suggestions to help accomplish that goal.