I've been wanting to do some embellishment on my clothes, so I started this project by pinning some water-soluble stabilizer on the back. Stabilizer was helpful when stitching such a soft garment, and the water soluble just happened to be what I had on hand. I can also see using a light weight fabric that would remain in the sweater permanently.
Here's the stitching from the back, with most of the stabilizer cut away. I'm wearing it like this, when I wash the sweater again, the remaining stabilizer will dissolve.
Here's a close-up of the stitching. As you can see, I stitched around some the holes, just to keep the fibers from raveling. I'm still wearing this sweater a lot, and I think sometimes about adding a few flowers to the front to make the embroidery look more intentional.