For mine, I used a basic iron shape that narrows into the tails. Most of the iron shape is loosely gathered up to form the folds, and the tails split up to that point. I used roughly two yards of fabric for the bow, and mine ends just above my ankles.

My bow has three layers: a bottom layer of black taffetta, an outer layer of red satin, and a layer of net sandwiched between the two for body. After cutting out the three layers, I placed them together satin-taffetta-net, and sewed them together, leaving a small opening at the top to turn everthing right-side out. To make the folds, I did a loose running stitch from the tail split to the top of the bow, then carefully gathered it until it folded like I wanted. To keep gravity from wrecking the folds & gathers, I cut a strip of black grosgrain ribbon to the right length and tacked everything in place to it in several spots.

I originally attached it to the skirt with two skirt hooks-and-eyes, but didn't take into account that it was also pinned to the dress from when I did that, so during our performance there was a slight sag problem because of the weight. To counterbalance that, I'm making a wider waistband for the skirt so it can help support it, and adding a third hook to the grosgrain ribbon to keep the center from drooping.