It's ok to eat a bit more nutritious food when it's cold - your natural body heating costs energy.
Cover your head when outside, your head loses an unreasonable amount of heat.
If your bed's too cold in the evening, buy a heating pad - a warm bed feels awsome.
If your hands get painfully cold, more excruciating pain may be waiting for you when they start to heat back up. To avoid the additional pain, put your hands under cold tap water first - I promise it's going to feel warm. Then increase the heat slowly until your hands are warm again.
An electric blanket is one of the best ways to warm up when you're "chilled to the bone". Layer them between normal blankets to make the most of the heat and keep them clean, and you can get whole body heat for a tenth the cost of even a little space heater.
There's an old saying, "If your feet are cold, put on a hat". You could have the nicest coat ever made, but nothing will warm a particular body part more than the body parts next to it. There's tons of blood flowing close to the surface on the head, neck, and wrists; having those areas exposed turns your skin into a blood-cooling radiator. So consistent, thorough coverage and tucking in layers will make your winter clothes warmer than the sum of their parts