I've inserted the first focal flower (yellow spider mum in the center of the grid. It may tilt to the side in the beginning - but that will be corrected as more stems are added to the arrangement. Notice I hold the extra stems against the center flower to determine how tall I want the flower to be.
Again - remove any leaves that may fall below the water before inserting into the vase.
Use the natural lines and curves of the flowers to advantage. The flowers in the beginning are the same height, but the side flowers are leaned out at a 45 degree angle to the center focal flower.
I take into consideration that closed buds will open later, so keep the flower heads balanced to the opposite side.
Remove the leaves from the bottom, leaving a few leaves at the top to fill out the vase in greenery.
I size up every flower stem before making a cut. I really don't want to insert and remove stems often, as this can disturb the arrangement.
If the stems are dirty, rinse before inserting into the vase.