This works for me down to -15C up to 2 hrs. of riding
Head - full balaclava (ski mask), Oakley sunglasses (or clear raquetball goggles) with anti-fog spray, Giro Ionos helmet with winter shield
Body - thermal base layer (for skiing), any 100% wool sweater (dirt cheap from trift store), Endura cycling jacket
Legs - thermal base thights (for skiing), MEC thermal cycling thights
Feet - point zero thin wool sock, then eddie bauer wool socks, Shimano shoes, SIDI thermal shoe covers
Hands - thin $1 store gloves, luis garneau typhoon cycling winter mitts
Also i use camelback for hydration since regular bottles freeze immediately. Wool is the key. It is really great in regulating body temperature.