1) Boil Ginger Root to make tea: some foods are naturally warming, this is one of them. As long as you don't have blood issues or health challenges that would make this unsafe for you, this is a powerful food to warm the body naturally. I prefer the actual root to pre made teas as it's a bit stronger.
2) The good ole hot water bottle, YES I have one! Put that hot water bottle in your bed at night at your feet and feel it warm you toes on up! Hot water bottles are healthier and safer than heating pads and for those sensitive types, it's best not to do electromagnetics in the bed if you want to sleep well.
3) Breathe deep! We tend to hold our breath when we are cold which can actually deplete our internal heat. Breathing deeply and consistently can help keep warm. And for those open to doing something a little different, in yoga we learn that the right nostril is our warming nostril, breathing in and out of it will increase heat (but best to do this in the morning and/ or during the daytime and not to do this before bed as it can also increase our thinking abilities).
Hope these little tips help you stay warm and cosy this winter!