I have a small class of 3 students on some nights. My students for this class had more than 5 classes with me in the past month. One thing they want to focus on was portraits and they specifically requested for one with flowers like how I usually do mine. I didn't take progress shots except of these 2 from my phone. Here's how my demo turned out. Washes were very light as the reference was a high-exposure studio shot.
The florals I picked were hard to draw like the Camellia so we freehanded them instead. A lot of illustrators do their freehanding more decoratively and loosely but since I do a lot of realisic work, I'm sort of impulsed to make it look as real as possible even without outlines. The only outline I made is for the outer border of the flower/s. The most imprortant areas are really the lowest shadows and highest highlights. Once you get these 2 down, it can solve a bulk of your problems, and of course, you have to maintain transparency while doing this (although the transparency would still depend on the scenario of your subject but it's still encouraged, especially for beginners, to gradually build up layers).