This is not the right way, but this is how I have done it. A combination of space heaters running 24/7. I put one in the kitchen, one in the bathroom, and one in the bedroom. Thermal curtains - closed at night to stop drafts and open during the day to get warming sunlight. Baked and cooked a lot and left the oven open after. I got a pipe heater rope and put it on all basement pipes. My water lines were mostly internal so I lucked out. Granted some rooms may still be 40 degrees inside.

While that was happening we applied for heating assistance. Just keep in mind that at any moment a space heater could malfunction and start a fire that kills everyone in the house. We checked the smoke detectors to make sure they were functioning but honestly every day is like a game of roulette.