I was waiting for someone more experienced to answer this. BUT here goes my limited experience.
It is similar to paper piecing. You sew onto a foundation like muslin although you can use up your "what was I thinking" fabric as long as it isn't too dark.
I learned to start with an odd number of sides in the center so you don't end up going around in a square. Then you sew the next piece on. If you have a piece underneath that sticks out you cut it off leaving a quarter inch seam. Press then move on to another piece.
As for the embellishments that go on top. You can put whatever you want on top. If you want to cover a spot that works.
Here is the link to some of my pictures.
http://www.quiltingboard.com/posts/list/11567.page