Solidago is a marvelous blend of bright green, with the yellow emerging as the flower matures.
You may have to remove some of the side laterals that will dip below the flower line, but don't remove any more than necessary.
Hold the flower upright against the vase. I don't want it to overpower the center focal flower, but rather fill in the center part of the vase.
So I place the stem dead down the center, clustered up against the first yellow spider mum.
Gently work the flowers down into the arrangement, trying not to disturb or dislodge earlier placements of flowers.