Using the photo I took at Shaker Village of the bowl of lemons, I've traced it on tracing paper and then copied that, enlarging it a bit and darkening it to show the darks where they need to be to work. This painting really needs those darks to be deep and rich to work so I started with the darks. If I don't get them right, no need to continue with the bowl and table.
Mixing my dark from just three pigments: French Ultramarine Blue, Perylene Maroon with just a touch of Quinacridone Burnt Orange to warm it up more for the darks that are brown but in shadow. The photo of the painting doesn't show how you can see the darks are warmer and cooler, depending on what I had in the mix.
I turned the photo and the watercolor sketch upside down so I could see the dark shapes without thinking about what they were. Here's the start: