A sizable portion of household heat can be furnished by a woodstove or fireplace insert if it's properly situated and installed. Open floor plans tend to utilize radiant and convective heat to best advantage, though stove or ceiling fans can circulate warm air to some extent. Avoid using older airtight stoves and inserts if at all possible they have high particulate emissions levels and may even be illegal to operate in some locations. They also don't burn wood very efficiently. Stop the draft.
Storm windows are a recognized pay-back investment in cold climates.
Aluminum-frame storms should always be installed with caulk against the window frame to reduce drafts. Hot water, high bills. If you use a gas or electric water heater, you can save a portion of your water-heating bill by wrapping the tank in an insulating jacket. Newer heaters should have a satisfactory layer of protection, but older units most likely could use the help. High temperatures aren't required for washing chores, and heat loss increases with temperature.