I have family in Houston. If your electric company is anything like your highway designers... you’re in trouble!! Jk...
Deca mentioned hot water bottles, and thats actually an excellent way to raise temps a bit. Greenhouse growers do so with sealed water drums in order to slowly release the heat and energy. If you dont habe a gas stove, though, that may not help much. If you DO have a gas stove, dont run it to heat your house... we’ve had some tragedies in Baltimore from people doing that in winter.
I’d hang a blanket over the window if you can, because that is where the cold air will come in. The insulation in your home
Will help keep the cold out and heat in if you block the drafty doors and windows.
If you are looking for a generator, make sure you run it OUTSIDE the house, or get a solar generator. I have a few Goal Zero Yetis and love them. Running a heater will use up too much energy ok a yeti, though, but you could run the heat lamp.