I'm no clustering expert, but I have been working to improve them over the last few years and I definitely see improvement! I usually start with three groupings on a page (sometimes one-I like and odd number for some reason!). I usually pick my favorite 3-4 flowers from the kit. More than that gets overwhelming. I like the clusters to coordinate but not be exactly the same. I just vary the size and layer order. Then I add foliage or two. Sometimes I'll add other elements to the cluster (tags, charms, wordstrips, etc.) depending on what's in the kit. I also don't think the clusters have to be big to be effective.
Three cluster example:
One big cluster example:
One with other non-floral elements mixed in:
