Thank you very much, HansDig, Helm, Nap, Andrew, Nicolae!
Unfortunately I don't have WIP pictures for creating a SBS. I'll try to do that on future works. For this one I'll try to explain a bit of the process.
For metallic parts I used Scale 75 metallic set. For Norman helmet I tried to obtain a smooth finish. I used thinner paint in order to obtain smooth brush strokes. After the base coat I used very diluted glazes with inks (black, blue, green, purple) in order obtain shadows and little illusion of reflections. I reworked some light areas in the end. For Saxon helmet I used paint straight from the bottle with rough brush strokes in orders to obtain a bit rough texture metal. I used three nuances of metal from dark to light adding some shadows and lights. After that I outlined with black ink all details of helmet. Next I used very diluted glazes of Vallejo smoke and inks (black, blue, brown) for simulating reflections and some wear. At the end I highlighted edges and nuts with brightest highlight mixed with white. Also I painted a few scratches here and there.
For clothes and leather I used Vallejo and Scale 75 acrylics. I started with a medium dark base color. From there I added lighter color for creating lights and a bit darker color for the deepest shadows. (For texture on leather and fabrics I used stippling and rough brush strokes.) After that I used glazes with different nuances (blue, red, ocher, browns) for creating color variations. In the end I touched again the lights for more definition, especially on the edges.
I hope these explanations will help. For any other questions please don't hesitate to ask.
Bogdan