I know the guys have mentioned it, but it is all about layers, staying dry and having something that stops the wind from getting in. You also don't want to get soaked inside from sweat, so those more expensive materials that breath and keep you warm are an option. I spent several years in the oil patch in all seasons and in the tropics in all seasons, but have been in an office for 15 years, I am sure the technology has improved.
One last item: If you can wear mitts instead of fingered gloves, do it. They are easier to keep warm, and stick a couple of those heaters inside! I do believe they have rechargeable chemical reaction heat sticks available, first google click was this:
http://www.amazon.com/HEAT-WAVE-Inst.../dp/B000E48LVM
