Do I shade emblems etc on surcoats using the particular colour of the emblem or that of the surcoat? E.G. white surcoat red cross do I shade the cross using highlights/shading for red.
When I have to shade clothing with any kind of emblem (i.e. heraldry) I always start by finishing the clothing with its shading and highlighting. Afterwards I tackle the emblem ending with darker or lighter lining depending on its position. In this way you can shade the emblem too and all the same create distinct borders between both surfaces. Make sure to keep everything subtle, though, feathering the lining towards the inside of the emblem. By doing so the emblem will look a bit raised and that's just the effect you want to obtain, because emblems are always (or most of the time) sowed on the clothing. IMHO this was certainly the case for crosses used during the crusades. So in this case finish the surcoat and then the cross, at least that's how I would do it.