TIPS, TECHNIQUES & TUTORIALS
Here I tried coloring over the grayscale cow with oil pastels and then blended them with baby oil. The key thing I learned was that you don't have to be too precise with the pastels because you'll be filling in the spaces when you blend with the baby oil. What is important is that you capture the highlights with your light pastels and the shadows with your dark pastels, then use a medium color pastel to fill in.
Specific techniques shown in the following time-lapse video:
Mediums used in the following time-lapse video:
Time-lapse video showing the cow from Beautiful Creatures being colored with oil pastels and blended with baby oil
Here is another example that has used this same technique