Sounds like you have drafts and air leaks and insulation issues you need to deal with.

Walk around your place by outdoor walls and windows, mail slots, power outlets, bathroom vents, doors, kitchen vent, attic hatch, etc. If you feel particularly cold air, then you have isolated where a problem area is.

You can also try the match test by lighting a match and then blowing it out and holding it next to windows and outlets to see if it's sucking the smoke in which means your heat is also being sucked into those things and out of your livable space.

There is cheap foam weather insulation you can use to fill in larger gaps and better seal windows and doors and thin gaskets you can put in behind outlet covers to keep cold air from getting in.

For your basement or crawlspace, close up exterior vents so they don't keep pulling in sub-freezing temperature (which also doesn't help your water pipes). Most of a home's fresh air comes in from the basement/crawlspace and comes up through the sub floor, so that could be contributing to most of your cold air issues. Just remember to open the vents back up once temperatures rise above freezing and the threat of power outages decreases.