Once I had the outline, I put down a background wash.
Then I put in the shadows with blue, mixing in some black for the deep shadows.
I added in some burnt sienna to warm the painting.
Then I added in the details with some black, including eyes, wrinkles, and a few more shadows. Once I added the shadow on the ground, the elephant became much more "grounded". The last touch was adding in the grass in the foreground and a hint of greenery behind.
I also improved the lighting that I was using to photograph it. That makes a huge difference, taking it from that yellow to actual white!