This will prevent the pipes from freezing and will save money on hot water heating costs. Have your heating system checked and cleaned regularly by a heating oil professional for fuel efficiency. Install automatic setback thermostats that adjust the heat to you schedule. Install exterior storm windows, including cellar storm windows. For windows that are rarely opened, consider installing interior storm windows.
Many systems are too large for the space being heated resulting in a considerable waste of dollars.
Replace standard curtains with tight sealing, insulated or quilted window coverings.