I like using leather leaf to fill in the largest part of greening in all centerpieces. Wholesale bunches are usually bundled by weight, but generally contain around 25 stems.
You can see that a single bunch is very large. I don't force my customers to buy 10 bunches at a time, rather single bunches so they can purchase only what they need and mix and match flowers and greenery.
Single stems have many laterals that can be cut off and inserted into the bouquet holder one piece at a time.
Make a clean cut with your floral knife so it inserts easily into the foam with no large holes.
Be sure your foam is fully saturated and secured in a holder or a narrow necked weighted vase. Bouquets and wet foam is heavy and you don't want it toppling forward during your designing.
Encircle the bouquet holder with a frame of leather leaf. This circle of greens will define the final size of your bouquet. The flower heads usually extend slightly beyond the greenery tips.
Fill in with the outer pieces outward and tilting slightly backwards. As you move into the center, begin angling the greenery forward, until the center pieces are pointing straight towards you.
This will give dimension to your bouquet design.
Even if you don't want the greenery to show (as this bride decided), you should still green in to cover the mechanics if you should be able to peek between the flower heads.
You'll notice I greened lightly - leaving room to be able to see where to insert those delicate calla stems.