I started my drawing in a fairly random fashion... I had just finished a similar accordion sketchbook that was a horizontal continuation. This time I wanted to go vertical. The idea was to start in the ground, and end up in the sky or space. I gave that up along the way, but here is evidence of my method... sketch in with a Copic marker (warm gray 10%). The sketch was a combination of from-the-head (most of the bottom tile) and referenced or photo-inspired random stuff. The pen I used is a brown 0.25 Hi-Tec-C gel.
This drawing was so detailed and small that I had to use magnification. I bought this CRUMMY device from Harbor Freight. Don't waste your $8 on it. The arm doesn't hold up... I went back and bought one of those white drafting lamps with a magnifier lens, where the bulb encircles the lens. FAR better for this work, and I've used it so many times since. The same lamp is sold elsewhere, but Harbor Freight was much less expensive.
A Peek At More
I knew I wanted to do something Celtic after drawing the girl, who was more than a little inspired by a shoot where Andrew Jones had done some amazing stencil tattoos on a model's face. The headdress and decorative tats were so inspiring to me I had to draw it. I changed a little of it to make it less of a ripoff, but I don't think I really did a good job of that. It's pretty obvious when you see the source image (I'm too lazy right now to track that down).
As for the Celtic stuff ghosted in up top, I dug around Google Images for Celtic Knotwork and artifacts to inform design and form. I also grabbed reference from those killer designs on the doors of Urnes Stave Church (Google it).
I put my hand in this shot for scale. You can see here how I literally draw up to the edge of the tile and stop... the idea is to take what has ended on the previous tile, and riff off of it for the next. No game plan other than that. It keeps the process really fun.
Beginning of the End
Here I am starting on what I considered, at the time, to be nearing the half way mark, but was ultimately the last tile. The heads were based on a stone African mask I am absolutely enamored with. I've redrawn and implemented variations of it in a few works, and will continue to keep using it... that etched flowing line is magic to me.