I wear two pairs of pants even indoors during particularly cold times, two pairs of socks too or just one of the really thick ones. If your feet and legs are cold it'll be much harder for the rest of your body to get warm because of the warmth your blood provides (blood gets cold when running through cold legs/feet and then the rest of the body has to warm it up again), so make sure your legs and feet are also well taken care of.

I have a medium-sized thick blanket that I use in my computer chair and in bed (under my duvet) and now I have another blanket for the couch so I don't have to be moving my one thick blanket everywhere.

Also got a pair of those socks/slipper things, totally worth it. They even make my feet too warm if I have them under the blanket too sometimes.