First you need to start with a nice smooth surface. This dark blue was built up over 3 or 4 very thin layers.
Next I sketch out the design at 1:1 scale. Check the proportions look right and it looks good.
Then starts the scary stuff. Initially I transfer the design onto the banner with very thin black paint. Don't worry too much if it's perfect as you can always adjust it later. The reason I use paint rather than pen or pencil is so I can find out at this stage if I can't do any of the shapes easily.
Next I fill in the block colours. In this case beige for the scrolls and yellow for the sword/star. Again make sure your paint is thin to stop any unwanted surface texture. I had to do three coats of each.
After the colours have been blocked in I start to put in the shading. In this example I used a brown wash (agrax earthshade) as paint to start to shade in the scrolls.
I finished off the shading/highlighting on the scrolls by using nuln oil wash as a paint in the very darkest areas, and screaming scull (thinned to wash consistency) for the highlights.
This effect is finished of with a bright highlight of off white.
The process is repeated on the sword blade and the details/borders are put on. I used a very pale grey as pure white looks too stark.
The jewel at the swords pommel is done exactly as you would a gem on a model. Highlight to the bottom right, shade to the top left and a bright spot in the middle of the shade.
Finally comes the lettering. I did this by brush though if you found a small enough pen you could use that. Plan this very carefully so that the letters fit on evenly. With the 'knights' at the bottom I started with the g in the middle and worked out from there...
So there you have it one freehand banner. All told the banner alone probably took 3/4 hours so not something for your rank and file but well worth it for a stand out piece.
As always comments and questions are very welcome.