Online Drawing Three, Lesson 4 is a drawing in oil pastels using the secondary palette.
Try to find three to 5 objects in purple, green, orange, and white. Remember you can combine pastel versions of the colors, bright intense versions, and darker versions. Consider covering the surface with one of the three colors as well.
A variation of this would be to use the primary color palette (yellow blue and red) if the secondary colored objects are too hard to find. For instance, bananas/lemons, apples/tomatoes and a blue pitcher or tablecloth would work.
Try to put things in front of things so you are able to show foreground, middle ground, and background in the still life. Use the negative shapes (around the objects) and positive shapes (the objects themselves) to figure out what goes where.