Unsurprisingly, people have always loved bright colours and this included the Normans. While we're mindful of the rank and profession of our impressions, when it comes to colours, we're also encouraged to use contrast and embroidery to emphasize the variety of colours we have. I like to use the colour wheel to illustrate how to do this. While shades of brown are always welcome, dyes like woad and madder were often used at the times - obtaining blues and reds respectively. A peasant can't afford the brightly coloured wools, which need to be dyed in several soaks, but can afford the paler or closer to natural colours of wool. While a priest and a king might both wear 'black', the kind of black matters. A priest would wear naturally dark brown wool, from black sheep, and a king would wear dyed black wool. Some hard to obtain dyes would be very restricted to certain classes but, since looking just a little wealthier than you are is desirable, attempts at imitation were always around.
At the top are pictures of some of our shields after they were varnished, my messy paint work sitting among them. In a chaotic battlefield, it really helps to have a clear signifier of who you are or things get very messy.