When your income is erratic (or even if it isn't), every household expense is subject to scrutiny, most particularly those recurring expenses that are too easily left on auto-pilot but really add up over time. Energy prices have been especially volatile during the past two heating seasons and for the majority of homeowners living in the Northeast, heating oil ranks among the top five expenses.

There's a great deal you can do to minimize your heating oil bill, from bulking up on insulation, winterizing around doors and windows and adapting to a cooler indoor environment.

Still, unless you're Paul Bunyan and rely solely on a fireplace or stove for heat, you're going to have to bite the bullet at some point to schedule a home oil delivery.

But before you dial 1-800-OIL-NOWW, there are still ways to economize. You can save a few bucks simply by shopping around each time you order fuel. Over the years, I've narrowed possible suppliers down to the three I know consistently offer the lowest prices. (If you've signed onto a contract that locks you into a set price for the entire winter season, that's another way to go, but it's also speculative and can backfire like it did last year when customers who signed fixed rate contracts last summer of over $4.50 a gallon got burned when prices began to slide in the fall. I stopped purchasing fuel in advance after the oil company I paid for an entire winter's worth of oil went out of business, but that's another story.)

When you shop around, be sure to ask the supplier if they offer a discount for paying in cash. (In my area, you can shave off another .06 per gallon by doing this.) I also make a point to fill up my tank in the peak of summer, when prices tend to be lower. This doesn't always guarantee a lower price, but with the exception of the 2008-2009 heating season, it usually works. And finally, when I have no choice but to order oil in the dead of winter, I try to wait for a relatively mild day to do so. The delivery man who came to my home today confirmed that doing so made sense and that prices do indeed dip with even a modest rise in temperatures. Most suppliers will honor the price they quoted you, even if prices are higher on the day when delivery takes place

During the past five winter seasons, I've tracked oil prices and usage in my own home. I've certainly noticed the ups and downs in prices. Looking at the five-year period from 2005-2006 to 2009-2010, my cheapest price paid for oil was in 2006-2007, when I averaged $2.14 a gallon. That must've been a relatively mild winter as well, because I used less fuel that year, 315 gallons, than any other year since then.

2005-2006
Average price paid: $2.19 a gallon
Total gallons used: 391

2006-2007
Average price paid: $2.14 a gallon
Total gallons used: 315

2007-2008
Average price paid: $2.74 a gallon
Total gallons used: 339

2008-2009
Average price paid: $2.78 a gallon
Total gallons used: 506

2009-2010
Average price paid so far: $2.36 a gallon
Total gallons purchased: 116 as of 12/16/09

The last two heating seasons took the biggest chunk out of my wallet. I paid an average of $2.74 and $2.78 per gallon, respectively. Last week's national average residential heating oil price was $2.76 per gallon, according to the U.S. Energy Information Administration.

And while my total usage remained relatively constant in every other year, when I consumed in the 300-400 gallon range, I burned 506 gallons last winter. I can't remember, but it must've been a cold one. (The Residential Energy Consumption Survey reported in 1997 that households consumed an average of 730 gallons of heating oil each season. Hopefully, we have closed that gap since then, thanks to improved home energy efficiency.)

Averages, of course, don't tell the whole story. Checking back on a post I wrote last spring, I see that the lowest oil prices I paid in the past five years was $1.99 a gallon April 2008 (ah, those were the days) and the highest was $4.24 a gallon in June of 2008. Who would have guessed there'd be such a dramatic spike in just three months?

All things considered, I didn't feel too bad paying $2.36 a gallon today.

How do your heat bills compare?