My feet are never cold with this regimen(down to about 20 degrees) I don't ride when it is colder than that.

Windproof Booties
Smart Wool socks
Slightly roomy shoes
toe or full foot chemical warmers

But this is the key!
You MUST be sure the rest of your body is warm. Your body will shunt blood away from your extremities if you start to get chilled. If you keep your core plenty warm your feet will stay warmer. I don't mean, just comfortable, but actually toasty warm.