For those who are in an area without infrastructure for the cold: Wear layers & a hat & socks & slippers indoors. Shut doors to unused or unheated rooms or cover them with blankets. Move everyone to one room and pile on the blankets. If you can, make hot food/drinks.

Use rolled-up towels or rags to put in front of doors to block drafts. Cover any non-direct-sun windows with blankets or thick drapes and cover all windows at night. Leave cupboards open where pipes are and if you have old newspapers or rags, wrap them around the pipes.

If the water's running, let it drip. If it isn't running, leave the taps on drip anyway and make sure the pipes you can reach have the cupboard doors or accessways open. DO NOT use a kerosene or propane heater unless you leave a window open a crack in the room it's in.

Never run a fuel heater while people are sleeping - heat the room, turn it off, bundle up, sleep, turn it back on in the morning.

This is what we do when the temps get ugly. It's currently -20F where I am and I don't know what the wind-chill is but it's really fucking cold. Spare fleece to the rescue to block drafts.

Our house was built for cold weather and we still have to do things to block drafts and minimize heat loss when the weather turns ugly.