A warm home on a cold day is a wonderful thing, but if you have noticed that it seems very hard to adequately heat your home, the idea of turning on the heater might seem less appealing. Rather than blaming the heater, though, blame your house -- it likely has several points where hot air is leaking out and letting cold air take its place. Here are some areas in your home that you need to check to ensure they're not contributing to additional cold feelings.
The Bottom of the Door
If your front door is just a little too short, you could end up with gaps around the top and bottom. The top can be taken care of by adding good weatherstripping, but the bottom can be a problem. While the door stop should help block some drafts, it's best to keep a draft dodger (or draft stopper) by your front door. This is a sack of filling (beans, styrofoam beads, etc.) that sits across the bottom of the door, blocking drafts from blowing in, and keeping warm air inside the house. You can make one yourself by sewing a long tube of cloth and stuffing it with beads, rice, or other material that will weigh the dodger down while letting it be flexible.
Also check your window weepholes. These are necessary openings that let condensation drain out of the window track, but they can be quite large. Adding some steel wool can decrease the amount of cold air that seeps in.
These are notorious for being drafty. All you have to do is light a match, blow it out so it actively smokes, and hold it up near an outlet plate, and chances are you'll see the smoke bend away from the outlet. Installing a foam gasket should work; if not, you may have to call a heating company or electrical contractor to see if they can further caulk up the outlet for you. Don't attempt that yourself because it's too easy to get caulk into places where you don't want it to go.
If you have an opening cut in the ceiling that leads to the attic (or to a crawlspace), it's entirely possible that there is a lot of hot air seeping through the opening around the door, even when the door is closed. There are special covers you can buy that will seal up the door (these are removable, of course). You should also check your attic and crawlspace insulation and replace those if necessary.
You can contact a heating contractor like Reid’s AC & Heat to see if they offer services where they go around your house looking for areas leaking heat. Once you find those, you can seal them up so that, next winter, it is a lot easier to keep your home at a comfortable temperature.