It costs me about 45 bucks to fill up my Altima, which gets 32 mpg. You absolutely have to keep up with the maintenance.
As far as home heating is concerned, we all have to worry (at least any of us that actually live in a clime where heating is necessary). My home is extremely old and drafty. It was charming when I first bought it, now it's just old and drafty, haha.
If you can, and if you don't already have them, get thermostats with timers as a start. If the house is empty during the day, have the heat set lower than you'd find comfortable, like 64 or so. If you have a timer, have it raise the temperature to 70 about an hour before you get home. Then, when you get home, and if you can stand it, lower it to 68 and keep sweats on. Make sure you dry your hair completely so you don't feel chilled. Use flannel sheets. Try to let as much sunlight in as possible during the day. Turn the heat down again when you go to bed, and if you use a timer, have it go up slightly before you wake.
If you have drafts in the windows and doors, and cannot repair the windows, put towels at the sill. Light candles, too. Romantic and they give off warmth.
If you like baking, do it when you can appreciate the warmth of the oven. In other words, don't bake and then go out, leaving a nice warm home. Eat well balanced meals and get plenty of exercise.
Above all, keep warm with layers, both on your body and on your bed. But, don't sacrifice comfort too much. If you have to, do without something else, like take out, or starbucks (or anything you treat yourself too that you really really could do without). It's not fair to work hard all week and not be able to come home to a comfortable house.
Me...? I plan to stay in bed all weekend in the cold weather, getting quality time with my boyfriend.