Based largely upon the method of JuanHidalgo Miniatures in his 'Eavy Contrast Marines video, but relying less upon actual contrast paints, this is how I painted the freehand on this miniature.

1. Basecoat the armour with Khorne Red .
2. Recess shade and paint the inside or the armor trim with a 1:1 mix of Khorne Red and Rhinox Hide .
3. Paint in the linework with your black of choice. I used Abaddon Black , buy you could use Black Templar . When it came to deciding what to paint, I Googled "colchisian runes" and looked up art from codexs and similar sources. I fleshed out most of the panels with these runes and then joined them up with lines and semi-circles.
4. Apply a chunky edge highlight of Khorne Red and Squig Orange mixed 1:1 to the inside of the shapes created by the lines.
5. Edge highlight everything again, moving closer to the black, with a fine line of Squig Orange .
6. With a 1:1 mix of Squig Orange and Lugganath Orange , selectively highlight corners over the previous highlight.
7. Add in final dot highlights of pure Lugganath Orange to the centre of the previous stages highlights.