A guest post by Anne Maertens from EnergySavvy.com.

Have you started closing your windows at night? That’s a good sign that it’s time to start getting your home ready for fall. An important part of your fall preparations should be weatherizing your home so you can enjoy a comfortable abode without having to sign over your paychecks to your natural gas, propane or oil providers.

Spend less than a hundred dollars on easy projects you can finish in a few hours, or invest in long-term solutions for your home’s energy efficiency shortcomings. Either route will give you a return on your investment in the form on energy and financial savings.

Quick and Dirty DIY

Doors – Use weatherstripping around your exterior doors. Not sure if you need it? Look at the cracks around your door. If you can see daylight through the seal, close up the cracks to prevent air from flowing in and out of your living space. Weatherstripping materials are available from hardware stores for less than $20 per door.

Windows – Right next to the weatherstripping in your hardware store, you should find window film for a comparable price. This clear plastic acts like a low-cost, temporary storm window. And all you need to install it are a pair of scissors and a hair dryer.

Other Leaks – Unwanted airflow can usually be found around older chimneys and electrical outlets on exterior walls as well. The best way to find leaks in your home is to have a professional energy auditor perform a blower door test, but if you’d like to try your hand at finding air leaks, hold a lit match near the area in question on a windy day. If the fire dances or blows out, you might have a problem. Depending on the leak, you can use caulk or weatherstripping to close the gaps. Don’t use caulk on movable parts.

Get Professional Help

The next three measures will not only have a big impact on your bills and comfort, but they will also qualify for the federal residential tax credit for energy efficiency, which is set to expire after December 2010.

Duct Sealing – If you have non-insulated ductwork located in your crawlspace or attic, you should have a professional energy auditor perform a duct pressure test to analyze how efficient your HVAC system moves heat through your home. If the only material sealing the gaps between your duct connections is duct tape, you’re probably spending a lot of extra money each winter to heat your attic or crawlspace, not to mention picking up dust and dirt and blowing it into your living space. Once your auditor has identified the leaks, a professional will be able to seal up and insulate your ductwork to help you heat your home up to 20 percent more efficiently.

Insulation – Properly installing insulation in your attic or crawlspace is one of the most cost-effective measures you can take to making your home more comfortable and affordable. However, the key to high-performance insulation is to make sure it is properly installed because if there are any gaps in the insulation, the overall R-value efficiency rating will drop significantly. If you can only afford to insulate one area of your home, insulate your attic. Not only will this have the greatest impact, but also attics are generally the easiest for insulators to access, which can also affect the cost.

New Furnace – About half of the energy you consume in your home is used for heating and cooling. If it’s time to replace your current heating system and you can afford the upfront costs of a 95 percent efficient (AFUE rated) furnace, you will see big long-term savings on your heating bills, especially if you combine the installation with the insulation and duct sealing mentioned above. A couple other quick and easy ways to keep your furnace running efficiently are to install a programmable thermostat and to change your air filter once a month during the heating season.

Besides the federal tax credit, which is equal to 30 percent up to $1,500 of the cost of energy efficiency improvements, you may also qualify for local rebates from your state and utilities. My company, EnergySavvy, provides a localized list of rebates as well as a free online home energy analysis to give you an idea of how much money you can save by improving your home’s efficiency. Or you can ask an expert about a project you have in mind.

This guest post was contributed by Anne Maertens with EnergySavvy, a nationwide company that provides a free online energy audit tool and a list of energy efficiency rebates and tax credits.