I've used yellow, dark blue, light blue and orange. I think it's a good idea that you use three to six colors at the beginning because it might be easier this way.
If you have a few rather similar tints in your color set, take them all and make color samples on paper to decide which ones you want to work on now, which ones resonate with you.
I've chosen yellow-orange colors of the sun – warm and energetic, and in contrast – deep calm, and cold blue colors of the night.
To create a good composition with the big buds I imagined a polka dot pattern with large dots and composed the flower's buds the same way.
I drew outlines of 3-4 big buds trying to place shapes evenly over the pages. I crop the form with the edge of the page.
I filled the big empty spaces between blooms with little twigs.
I suggest choosing different shapes of the leaves to increase shape contrast.
For example, I drew one stem with narrow long leaves and another with wavy a bit oval leaves. This creates a contrast of shapes and makes the rhythm more interesting.
In the beginning I've colored the background with a wide tip orange marker. After I outlined the main shapes of plants
Coloring the leaves. I start coloring from the background to the upper leaves.