First, you will need to cut your crepe paper into three different types of strips. The petals should be cut like an oval with a neck. Leaves should be cut with a pointy top. Once you have cut all your petals, it is time to shape them. Begin by using the pad of your thumbs to stretch the petal where I have drawn arrows.
In the previous step, you just stretched the petal where the blue arrows are. Now, you need to move closer to the top and stretch where the red arrows are. Finally, you want to create a ruffled edge on the top of the petal. Do this by holding the top of the petal between your thumb and forefinger with both hands, and twist away from each other, almost as if you were trying to rip the paper. The purple area notes where you should twist away from yourself while the green arrow should be twisted towards yourself.
Repeat this with all 20 petals. Now line up your petals with two rows of five small petals each and two rows of five large petals each. This will help you keep track of your layers. Begin to wrap your petal around the wire stem and securing it into place with the florist tape. This is how it should look when you have wrapped the first petal.
When you add your second petal, wrap it so that the petal covers the seam/opening of the first petal.
Make sure that your layers overlap each other with one side of the petal inside of another. This way, the petals can support each other. Once you have finished your last layer, pull and stretch the petals apart to make the peony bloom to your liking.