That is until I found this awesome series of articles by Ron.
making cardstock banners for 40k
making cardstock banners advanced
They have really helped me and I now feel confident to try making some for my personal armies, Ron you are the man once again!
I Thought I'd show this picture to show how I painted the detail over the pencil lines and then went back and blacklined with a brush to edge the detail and neaten up the banner.