On to Santa's details!
I started with the gold trim at the top and bottom of the navy area on his clothing (skirt? robe? tunic? what is this?). This is simply a heavy gold braid, perhaps a size 16, couched with a smaller metallic gold thread. In this case, the couching thread is the now-obsolete DMC Fil Or, but a size 4 braid or metallic floss would have worked.
The same threads were also used for couching the swirly design on the lower portion of Santa's red robe. I deliberately simplified the path of the right side of this line of couching since something else was going to go over it.
Instead, I kept the "spokes" of that web and turned them into fake bullion knots. I simply wrapped each of the spokes with the thicker gold thread, careful not to catch the red threads underneath everything. Then I added lazy daisies in between each of these spokes.
Unfortunately, since I no longer had a solid flower there, the original swirly line showed through the now-airy flower. It looked strange. I very carefully cut the couched thread in the middle of the flower. I pulled the thread out from under the flower and brought the ends to the back of the canvas on either side of the flower. Fortunately, there were only a few couching stitches used in this area. I was able to pull a few to the back, but a couple are still lurking underneath the flower. They're not visible, and that's all that matters.