I thought this was a good article from Keith Pandolfi at This Old House.
1. Choke Your Chimney
How To Save Spend a little, save a lot, or spend a whole bunch and save even more. Here are 10 ways to shave your energy bills year round. Sure, it's nostalgia-inducing and all, but when it comes down to it, your fireplace is terribly—make that laughably—inefficient. According to the Department of Energy, a lit fireplace sucks about 24,000 cubic feet of furnace-heated air up your chimney each hour. Bonus: It's replaced by cold air that comes in the opposite direction through the same opening, causing your furnace to work extra hard to keep your house toasty. Still, we love gathering round the hearth as much as the next guy. Just remember to turn the thermostat down a little when you use it. Also, crack a window in the room where the fireplace is located and then close the door, so it doesn't suck too much warm air from the rest of the house. And remember to close your damper when it’s not in use.
2. Seal Air Leaks
How To Save Add up all those overlooked cracks, gaps, and openings around your windows, doors, plumbing, and wiring, and you may find your house has a hole the size of a Mack truck. Seal it up, and you'll save more than 10 percent on your heating bills. Start by caulking or weatherstripping around windows. For added comfort, pick up a product such as the 3M Indoor Window Kit at the hardware store. Resembling Saran wrap, the plastic sheet costs about $20 and can be discreetly stretched over windows using double-sided tape, blow-dried for a tight fit, and peeled off come springtime. It can increase a single-paned window's R-value by up to 90 percent. Fill in cracks around door frames with caulk, and while you're at it, install a screw-on or adhesive-backed door sweep. Use expanding-foam sealants to fill in larger gaps around plumbing and electrical work, especially where pipes enter your house through exterior walls. Tackle energy suckers in overlooked places, too—like exterior wall sockets and switches. You can block them up using fitted insulation pads. Just unscrew the switch plates and pop the pads into place.
3. Show Your Heating System Some Love
How To Save Soot buildup, dusty or poorly lubricated fans, flickering pilot lights, and loose fan belts can add hundreds to your heating costs each year. Getting your furnace tuned up regularly by a heating contractor can do wonders for both your wallet and your overall comfort. Natural gas–powered systems should be serviced every two to three years, while oil-fired units need a tune-up every year, since they burn dirtier. To make your system even more efficient, prevent heated air from leaking into your attic or crawl spaces by sealing ductwork with mastic duct sealant—a nontoxic, paint-on material—or foil-backed tape. Doing so will reduce your home's air leakage and could save you a bundle in heating and cooling bills.
4. Take Cheaper Showers
How To Save Next time you take a shower, remember this: Heating water accounts for up to 11 percent of our utility bills. If your water heater is more than a decade old, that number could be even greater. Switching it out for a new, more efficient electric storage model could save you 10 to 20 percent on heating bills. You might also think about gas and tankless units, which save 30 and 40 percent on water heating, respectively. And let's not forget solar water heaters. At $3,500 to $4,800 installed, they're more expensive than conventional heaters, but they have longer lives (about 20 years) and pay for themselves in energy savings in about half that time. If you're not ready to buy a new water heater just yet, ratchet up your existing unit's efficiency with a water-heater blanket. It costs just 15 bucks and will save you between 4 and 9 percent on your heating bills.