From a backpacker magazine article.
6 tips to keep your toes warm:
On the trail:
1.
Put on a hat: When temps plummet, blood abandons the extremities to heat your core and brain. A hat helps circulation return to the toes.
2.
Wear waterproof gaiters: Calf high models provide more protection against wetness
3.
Do pendulums: If your toes go numb, swing your legs vigorously to force blood to your feet.
In camp:
4.
Change your socks: Then put on booties
5.
Make a heater: Fill a lexan bottle with boiling water, wrap it in fleece, and nestle it into the foot of your sleeping bag.
6.
Warm your boots: tuck the insulated liners inside your bag. There's nothing worse than shoving warm feet into frozen shoes.
Tip from a leader of the Skagit County Search and Rescue team:
WaterBlocker Socks. There are many "waterproof" socks (most of which she's tried). These socks in particular have a wetsuit seal at the top that keeps all water out. Wear wool sock underneath and even if you step up to your hip in water your feet will stay dry.
http://www.danalco.com/htmls/products/products.shtml
Tip from Andy's friend Amy:
Put a few hand warmers into the bottom of your sleeping bag at night. I did this at Whipsaw and it made a huge difference.