The trick is to use thin layers, in decent insulating materials. And not to have things too tight, as this cuts off the circulation, and causes even more problems.
I use a pair of thin silk gloves under normal mid-weight gloves, and double-layer army socks if it's dry, or Sealskins if there's a chance of getting wet feet.
Layers mean you can add or remove them as necessary.
You may have low blood pressure, like me, so extremities will get cold quite quickly. this is exacerbated by the fact that your fingers and toes aren't doing much, so the blood isn't flowing around enough to generate enough heat.
In really cold weather, I find that a pair of stout leather 'boot' trainers, with good socks on underneath, and flat pedals, better than using SPD shoes. With SPDs, your feet stay fixed to the same point, and your toes just aren't getting the blood flow they need. And SPD shoes tend to be a bit too 'breathable' to keep out the cold. Maybe 'winter' SPD boots are the answer for some, but I've never tried any. You could try those little neoprene bootie things I suppose. I have no experience of them.
Other than that, you'll have to keep wiggling!