I cut up the ribbon in progressively smaller squares and cut off the corners of each piece. I've done the squarer look too but I like it more rounded, then when it melts it's not too black.
I started at with the largest one (it gives me an idea of how big the flower will be) and melted the edges of the whole thing. I've done some with more jagged edges for a vintage look but the rounder edges make it more neat and cleaner lines.
I put the earring through the center to hold it all together the way I thought looked good and I sewed the petals right through the middle. I also added a small piece of flannel material, about the size of a quarter or fifty-cent piece, and sewed that to the bottom so that it's more supported in the center. It also helps it not slip so much against slippery hair. Better grip! It looks best if the top petal is glue-gunned instead of sewn, so you can cover up all the stitches. I took out the earring, clipped off the metal stem so it's flat and glue-gunned that on the top petal in the center. Now I just have to add an alligator clip