Standard stuff you need first:
clock-thermostat, with max setbacks possible. (Electric blankets for
the pampered.)
aquastat setting as low as will work. (maybe 130F vice 180F, and varied
by month.)
automatic stack damper. (can give you 50% savings)

These can yield 40-60% savings for small, one-time charge.

Zone-off areas where heat is not needed. Like, even with Alum foil rad
jacket.

Seal around all doors and windows, tightly. And find and plug all the
other leaks, paying special attention to those at upper and lower
extremities of house. Chimney effect. This is really cheap, makes
things v. comfortable w/quick payback.

Layer-on more attic insulation if advisable.

That's pretty much it for the quick-payback, cheap stuff.

Next would be insulation in exterior walls. Replacing old mouse-fur
insulation for full-thickness R-13 makes a huge difference.

Single pane windows are candidate for high-e inserts. Another huge
difference.

Additional heat source like pellet, corn, or wood stove might now come
into play. Most simply for heating air. Many pellet stoves can vent
through wall. Forget this year, and plan ahead. For when stoves and
pellets will again be available. (Pellet stoves are also v.
low-emissions and ~90 or more % efficient, from tech data.) Wood stoves
meet needs of some of us just fine, those used to chainsaw, maul, and
sweat.

Forget trying to put this in essentially uninsulated masonry basement,
or plan on insulating stove area.

Enjoy staying warm,
J