Use the gridding of the foam head to help keep your stems placement even. Starting with my first flower stem, you can see it is inserted right into the very center of the top circle of the grid.
Carnations are available in purple shades from very deep to pale lavender. Start inserting the flowers in between the dark purple flowers already in the design.
Again, I circle around the design, spacing out the placement of the lighter shade of carnations.
Keep an eye around all sides of the bouquet, keeping the flowers spaced evenly around the center.
I always suggest that designers work up a "recipe" for each bouquet before ordering their flowers. That way you know out of your ordered flowers how many flowers are set aside for each bouquet. To keep designing until it "looks good" can short you on flowers for the rest of your arrangements.
I provide a free Wedding Flower Calculator so you can keep your flower budget in line and order the correct amount of flowers that you need.
Keep moving around the design, inserting the lighter flowers.
You have room for about nine stems in between the darker flowers.
Here's view from the top.
Here's the top view after the first dozen dark carnations, and then the additional nine lighter colored carnations were in between those flowers.