Cold feet is my greatest setback to cycling in the winter. What has helped most for me is the use of doggie poop bags. Yes , I am not kidding. I get the bags from the city park. you can also use freezer bags or bread bags, but the ppoop bags fit my feet.
So, I put on a pair of wool socks, slip on a poop bag, then my cycling shoe. The cycling shoe has a neoprene winter cover. Over that I will then put one or two more poop bags over that.
The bike clips go through the bags when you clip in.
It doesnt look really stealth, but it has allowed me to ride on days I normally would not be able too.