Heavy-weight merino wool or synthetic baselayer (1 if you run hot, 2 if you run cold). Baselayers are the tops closest to your skin.
Midlayer, such as a sweater or puffy jacket. Down puffy if you run hot, synthetic puffy if you run cold (or if you're a vegan.
Outer layer, a shell like a rain jacket if you run cold and/or insulated, water proof/resistant jacket.
No big, heavy coats, because they're not easy to pack in your bag and too heavy to lug around.
Merino wool or synthetic baselayer (such as long johns)
Insulated pants, waxed pants, or cords as your outer layer
Denim is not recommended.
Sturdy, waterproof hiking boots.
Gaiters to prevent ice and water from getting into your shoes.
Wool socks. Always pack an extra pair of wool socks, because your feet always get wet and cold no matter what kind of boots you wear.
Headwear. Something you feel comfortable in for prolonged periods. You should expect to wear your headwear the entire trip and certain fabrics may cause allergies or rashes.
Gloves. Optional hand warmers.
Flashlight (because it gets dark earlier, this is recommended as standard).