My students remind me of how difficult it was for me to draw and paint flowers with their many petals. My remedy then was to draw them over and over until I started to be able to "stay cool" in front o so many layers and shapes and I actually started to get them all on the paper. I did this with a fine felt pen so I couldn't rub it out, which also gives you confidence with practice. The rubber will not be needed much after that.
Today I try to teach the short cuts, if any, of how to render flowers and how to see in general. I explain what to look for to respect the shape (the contour) of the flower and the most important; the shadows. How to simplify and link shapes (shadows int this case) a maximum. To "paint the light" is the order. Do it by painting the shadows, after that you can eventually ad very light shadows in the light side of the flowers. To keep the painting luminous use light colors ("diluted" in watercolor painting) If your shadows are too dark it might not look credible. The light, mid and darker tones have to be related to make one shape. If one of those stands out too much we won't see the whole shape as one, that part will then not fit in the flowers harmony.
Stay "bold" in the gesture when painting, feel active, not passive and avoid fiddling with the brushstrokes or details. In the beginning you can use one color only, later mix a blue, red and yellow in different quantities and with more or less water to make luminous grays.
I hope you "see" what I mean and that it might be helpful...