I actually think Wilton's way is rather hard to achieve
Oh how I hated to have to teach that!
I prefer to do them in b'cream right on the cake, using them as a fill-in flower to a floral bunch. Generally when I made a Roland Winbeckler sheet design.
The are sooooooooo quick and beautiful accent to most bouquets.
Use tip 80 or 81 with the 1/2 circle opening facing against the cake. Pipe a quick, short (1/4") line; continue pressure while piping up right on top of what you just piped, then come down again - this time only about 1/2 way while relaxing pressure. At the end pull away (downward) sharply to form points to the end of the blossom.
So just remember, down, up down and you will have a great filler flower