If you want to make an elegant-looking fabric rosette, with no raw edges showing, first sew a long tube (maybe 30" or so) of fabric, about 3/4" to 1" wide. (The length of your tube will determine the size of the finished rosette -- err on the long side if you are unsure.) Press the seam allowance open, the turn the tube right side out and press it flat, with the seam along one edge.
1. Tie a single knot near one end. With needle and thread, stitch the knot, from beneath, to a scrap of buckram or heavy-duty interfacing (not the iron-on kind), at least as wide and tall as you want the final rosette to be.
2. Take the long tail and pull it upwards, then take two securing stitches through the inside edge of the tail, near the knot.
3. Working around the knot, pull the tail around again and take two more securing stitches, near the knot.
4. Twist the tail -- or don't, this is an organic process and really just based on how it looks as you go. Take more securing stitches.
5-7. Work your way around, twisting or flipping the fabric as you wish, taking more stitches through the buckram or interfacing, to secure the rosette. Keep going around in a spiral, trying to keep the shape roughly circular, until you are satisfied with the size of the rosette.
8. Flip the rosette over and trim the buckram as close as possible to the stitches you've made.
9. Tuck the end of the fabric tail underneath the rose, secure with stitches, and trim.
10. A lovely finished rosette!