We just got through a summer of fretting about $4-per-gallon gasoline. Now, as temperatures drop in Michigan, another worry looms: Heating bills that could rise as much as one-third over last year's.

Households that use heating oil for fuel are projected to be hit hardest. Those families will pay about 36% more than last year, averaging about $2,600 for the winter, according to federal government forecasts.

Those using natural gas -- the most common heating fuel in more than 50% of U.S. households -- are projected to spend about $1,060 on average during the winter months, up 24% from last year.

"There's going to be real sticker shock this coming winter," said Mark Wolfe, executive director of the National Energy Assistance Directors' Association, which represents state-run energy assistance programs for people with low incomes.

September is a good time to get your heating system checked and cleaned. As temperatures drop, service technicians will be in demand, and it may take a while to get repairs done. Plus, heating and cooling systems should be checked about once a year to keep them working efficiently.

You also might consider getting your home professionally inspected for maximum energy efficiency. Identifying the deficiencies and fixing them can save you up to 30% on energy costs, energy experts say.

The good news, said Terry Townsend, former president of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, is that people don't necessarily have to change their lifestyles to save money on heating costs. They just have to change the way they use energy.

Here are some tips:

Is your house well-sealed?

The total energy that escapes from your house through leaks each year adds up to about the same as "leaving a window open all year round," said Maria Vargas, spokeswoman for the Environmental Protection Agency's Energy Star program. As much as 15% of air can be lost through leaky ductwork alone.

Handy homeowners who know where their leaks are can do much of the work themselves -- using foam and caulking to seal up gaps and cracks, putting weather stripping on windows and doors, and insulating pipes and ductwork.

Insulate, insulate, insulate

Your local utility will be able to tell you how much insulation you should have, Townsend said, and proper insulation will help keep warm the air your heating system produces.

A word of caution: Make sure you aren't adding a moisture-trapping vapor barrier to one already in the existing insulation. That could trap the moisture that has slipped by the first barrier and get the insulation damp, he said. Also consider insulating your hot water tank and at least the first 6 feet of piping with jackets available at hardware stores.

Control the temperature

One of the most important things a consumer can do is purchase a programmable thermostat. Most cost between $30 and $100 at hardware stores and can save you about $180 a year in energy costs. You can program these thermostats to turn down the heat when nobody is home. Visit Energy Star's Web site (www.energystar.gov) to see which type fits your needs.

Also consider a humidifier if you live in a cold and dry place. Moist 68-degree air feels a lot warmer than dry 72-degree air, allowing you to keep the thermostat lower.

Window, furnace replacements?

More expensive projects -- such as replacing windows or installing a new furnace -- only make economic sense if the items were due for replacement anyway, experts say.

For example, spending thousands to replace your windows is not particularly cost-effective, because even the most energy-efficient windows still lose heat, said Mike Rogers, senior vice president with GreenHomes America based in Syracuse, N.Y., which performs energy audits and installs upgrades.

Update your appliances

Fifteen to 17 years is the average life span for most equipment, Townsend said. After that, maintenance costs start going up, and you're better off investing in newer, better equipment.

Vargas said Energy Star reviews and labels more than 50 kinds of products -- ranging from lightbulbs to appliances -- to guide consumers to products that are the most energy-efficient, high-performing and cost-effective.