Thanks,Ink on velum?
Charcoal on canson?
Lucigraph or slide from your photo or others?
It looks great. I love the perspective on the shell decal. I can see you are very good.
Do you mean that you project the photo on the paper and trace? That is how I do it. If you are drawing freehand with no projection, are you using the grid system? Are you using ellipse guides? We do that with large mural paintings. To get perfect perspective I need tools, working from the horizon line in 1, 2 or 3 point perspective. A long straight edge or string helps work out large murals.