As a born-and-raised Oregonian, the word "layers" pretty much defines my childhood wardrobe. To this day I base both my styling and purchasing decisions on how easy they are to layer. As a result of 20 years of layering, I consider myself an expert on the subject. As the year turns to winter, take my advice and layer up to ensure maximum comfort in the colder weather.
It sounds silly, but you have to start with a thick and/or tall pair of socks to really layer correctly. If your feet aren't warm, there's no way the rest of you will be!
One of my least favorite things about winter is that most buildings overcompensate for the cold outside by making inside way too warm. Avoid the "transition sweats" by wearing a tank or short-sleeved shirt underneath everything that you can strip down to upon entering a warm building.
Like a long-sleeve shirt but easier (and more acceptable) to take off in public if you find yourself overheating.
I wear my cardigan over my sweatshirt and typically take it off with my jacket. Just remember to hold onto any long sleeves you're wearing underneath to prevent them from sliding up under your cardigan.
A basic coat is a necessary basic staple to have in your closet: you'll never go cold for fear of wearing a mismatched outfit.
If it gets too warm, unravel it and let it hang from your neck. I also use my scarves as a bed for Luxe when I take them off inside, say, the library.