I'm pretty much always cold and poor as hell to boot. I swear by hot tea in giant mugs for my hands and a heat pad for my feet when I'm just sitting around. I try to keep busy enough during the day and alternate between times of sitting and standing (due to body issues), so I tend to keep warm enough in the afternoons, but at night or on an off day...yeah a hot drink and heat pad for the feet do the trick nicely. Also, if you have a large sock around, fill it with rice and either sew up the open part or tie it off. You can microwave it (if you have a microwave) and those things hold heat for a bit and can be nice to have by your feet when going to bed...or to use whenever really. They're pretty nice to. And has been mentioned, layer up. I always have pants on under my pants, at least one pair of socks on, a beanie, stuff like that goes a long way as does a nice, thick hoodie.