I'm Currently working on another geometric caparison pattern and thought I'd share this WIP to hopefully illustrate the method I use.
I prepare the base colour then apply the brown dots in rows, this way, if one is out of line you can just overpaint and start again having not lost too much time and effort. Each dot then centres the motif in the grid, in this instance I'm using stylised stars but I'd do the same if they were fleur de lys or whatever.
The other thing to add is to paint the area as a whole rather than each bit of attached caparison, it looks better and replicates what tended to be done; an overall design in component parts.
Finally, keep the rows straight rather than bending them around the contours, this ensures the geometrical look.
More soon hopefully
Stuart