Firstly, I would say you need to figure out why your feet are cold? ALL the above answers are great guides, Make a checklist of the things that everyone mentions and see what is different between what you do and they do.
Next, Keep you core warm. layer your core to keep it warm, old wool shirts from the thrift store cut into vests will help for quick on/off layering. Wear a neck gaiter and some good gloves/hand warmer. I know it sounds crazy but if the rest of your body is warm enough your toes aren't as bad.
Make sure your feet start dry and stay dry! You can't win if your feet start or get wet. It's a loosing battle already. Get a boot dryer and if your feet get really sweaty on the walk in consider wearing a light sock until you hit the stand then changing to the heavier Liner/sock combo. I don't believe my feet EVER sweat with the liner/wool sock combo unless the wool sock is TOO heavy. I have some extreme 200 wool socks that are like booties! I bought them for still hunting in the snow in PA.
Now for the feetsies, Loose fitting boots with an appropriate thinsulate (600-1000 I'd say), insulated liner socks, appropriate weight wool socks (I would start with 100 weight or hunting style) then protect your feet from the elements as everyone else has mentioned, artic shields, sleeping bag, beanie over the feet (although I am concerned this one might get wet). Also, some people like to place a piece of carpet on the base of the stand to be sure the boot doesn't touch the metal (The metal transfers the cold into your boots.)
I also like the idea of the toe/hand warmers on the OUTSIDE of the boot under an artic shield.
