And for the first Russian units I chose the Belgorod (or Belogradski) flag.
I wasn't going to move to the more colourful units so soon, but after looking through the uniform sources I'm going to do a couple of yellow uniforms. This yellow and red combination will eventually be the Kiev or Ingermanland regiment.
The yellow uniformed dragoons will become the Archangel regiment. I don't know about the green unit.