Keep heat in and cold out by cutting a pool noodle in half lengthwise, wrapping it in fabric, and sliding it under your door. It'll stay put all winter, and you can re-use it at the pool come summer. (But we recommend you spring for a new one.)
Another two words: Obvious, right? Stay toasty on schedule, so you never go home to a living room that's colder than outside. You can even do it with your smartphone.
Not everyone has access to adjust the thermostat in their apartment or office building. If that's the case, you may need to outsmart the device by making it "think" the room is colder than it actually is. Putting ice near it often does the trick.
If you're not wearing a tank top or going sleeveless, your windows shouldn't, either. Replace thin curtains with heavier wool or fleece drapes in the winter. But be sure to open them on sunny days for free heat.
Using your oven heats up the whole house. You'll feel even cozier if you invite friends—and all their body heat—over to eat four dozen cookies.
If you're already interested in composting, here's another reason to do it: The microbial breakdown of organic material produces heat. Some people use it to warm up showers and greenhouses, but even small-timers in studio apartments can feel a difference.
It's intuitive, but fluffy blankets should be closer to your skin. Thin, dense blankets should be on top to prevent convective heat loss. Bonus tip: Don't put your bed directly against an exterior wall. You'll be warmer if you leave a little space.
You could just buy hand warmers, but you'll radiate pride and self-sufficiency if you make them yourself. All it takes is two Ziploc bags, water, and calcium chloride ice melt pellets from the hardware store.