I still haven't decided about the three large flowers, so I decided to begin toning some of the leaves and flowers on one of the paintings today.
My process is this: First I paint the object in bright colors, then cover with Holbein Gray of Gray. When the paint is still tacky, I wipe it off, leaving a nice dullness to the color. Then I tone it with black and white. When all dry and the sense of depth is to my satisfaction, I may glaze over it with a new color to give it more interest.
That said, here is an example of each phase in process (except for the final glazing.) Look at the purple flowers. The middle one still has only the base color. The left one has gray over it. The right one is beginning to reflect some value, done with black.
The image below shows where I ended my session today. Most of the leaves have been worked upon, as well as the purple flowers. I changed the berries (upper left) to lavender from blue to balance the colors a bit. There is still a long way to go.