I a bought plastic Christmas ball at Hobby Lobby, I don't put anything glass on our tree since little man was born. I filled it with tiny fake snow I found at Hobby Lobby in the same section as the plastic balls. I free handed the face with acrylic paint and pulled the baby sock over top. You could use something to adhere the sock to the ball but mine has stayed on just fine as is.
I cut off the tip if the sock where the seam was, in order to put the hook on the ornament.
Once the hook is in place take the tip of the sock you cut off, stretch it out, and use it to tie a knot around the top of the ornament.
Use your scissors and cut strips down the sock all around.
And you're done! simple and quick and oh so cute.