Don’t overtighten your shoes. Lots of people seem to crank up their shoes to make sure they can’t move on their feet but then they cut off the circulation and so get cold feet. If you’re putting on thick socks you need to loosen off even further.
+1 constricting your feet with thicker socks and ratcheted down fasteners will just bugger blood flow, cause discomfort and numbness without much real benefit.
A comfy fitting shoe / sock combo with extra insulation/water/wind protection on the outside (overshoes) trying to trap more heat in the shoe and keep the weather out as far as possible makes sense to me…
Never know seal skins socks to be much use
The handwarmer tip above is a new one to me, but I like it, I might give that a go when the weather turns a bit more…
The heated insoles thing sounds good, but I’m not too sure I fancy having cheap far eastern electronics strapped to the sole of each foot…
I also tend to leave all my footwear, shoes socks, overshoes on a radiator before a ride if I have the chance, starting a ride with warm feet helps quite a bit…
I shall look further into some of the ideas above though…