Today I put a bit of work into the bead embroidered collar.
Before filling in a space with black size 15 beads, I color the stiffened felt with a permanent marker. Matching the background to the beads is important when filling in a flat area. While the background need not match the foreground perfectly, it should be colored to be unobtrusive. No matter how tightly placed the beads are, there will be gaps where the background can show through, and the white felt would be particularly obvious. I used a fine-tipped Sharpie marker.