I grew up in a giant old house in southern ohio where my parents kept the temps low in the winter because OMG EXPENSIVE TO HEAT and have always run cold.
1. Figure out what bits you need to keep warm to feel warm and address those. For me, this is weirdly mostly my joints. I don't care about having cold toes, but if my ankles feel cold, I'm miserable, etc. So I like giant loungy pants that shroud my ankles, giant fuzzy wool socks, that sort of thing. Also think about where you are losing heat. I don't need them to be heavy or super insulated, but wearing a pair of slippers helps keep my feet warm because I'm not losing heat to the floor when I'm walking around. Wearing a hat helps reduce heat loss from my head, that sort of thing.
2. A hat makes a huge difference for me, especially when trying to fall asleep.
3. +1 to rice sack/heating pad/cuddly animal. Having your immediate area warmed up is key! Warming up the bed before I get in is also a huge help.
4. +1 to most of the materials mentioned. Knit acrylic blankets or fleece blankets have always served me well when I'm sitting around all day. If you come across a down throw, those things are amazing for lap blankets when it's really cold. Wool clothing, especially fuzzy socks and baselayers are great. I layer up like crazy, and that helps a ton.
5. I bought one of Ikea's warmest comforters a few years back and it is a gamechanger! I started out with their polyester fill, and that was great for a while but washing it does send it on the fast track downhill. It's still good for indoor temps in the 60s, but it developed cold spots so I picked up on of their feather/down ones when I was living in a particularly uninsulated house in a room made mostly of windows, and I can actually be hot while sleeping sometimes for the first time in my life. IDK what the longevity of it will be compared to other brands/pricepoints. I switch the two out depending on how cold it is.
6. And +1 to getting up and moving around. It really helps, even just walking across the room.
