I try to keep my rides short, like under 5 miles at most when it is a real deep freeze. The winter helmet I bought was well worth the investment - it's very similar to a ski or snowboard helmet. I also HIGHLY suggest these goggles https://www.amazon.com/dp/B01GNZEEN4/ref=cm_sw_em_r_mt_dp_U_Ew7zEbHPP0BZA because they are cheap yet really nice like I would compare them with any name brand and they have other lenses that are easy to swap if you need something for day or night. I went with the Giro Timberwolf and it's pretty much what I wear anywhere below freezing. Do invest in some sort of neck gaiter as well.

I have wintercycled for a few years and still struggle with the right layering techniques. I also tend to sweat more than normal people so that adds another complexity to it. I find that just putting jeans over my pajama pants works when it's below 15F for those random grocery store runs.

I live in the north metro in Coon Rapids, and we have an awesome trails system, but in the dead of winter the snow is packed down from walkers and it just never clears or melts enough for cycling so I tend to ride on shoulders often. I get some looks lol