I really like the photo ReNae, I wish I had the expertise to comment on oil, but I am way too much of a beginner! Have you done any of these like William Whitaker's
NuPastel Technique?
I think if you pushed the values in the photo's a tad bit, it would be a good study for the Nupastel or charcoal. I am not sure what the rule is when it comes to reference in one color translating to full color, extra tricky I would think.