Finished another! This one is for the Maple Valley Arts event.
My first step was to flat-shade the shadow on the lime, using a mixture of colors from the dark end of the yellow string and the warm green string. I used a bit of paint from the blue string to blend and lose the bottom edge of the lime in its shadow. Same for the lemon.
Then I painted the lit portion of the lime, and then went back and added reflected blue light to the form shadow of the lime and the reflection of the lime in the lemon’s form shadow.