"I'm awful at coloring" That's rather harsh and in my opinion, Not True , This a lovely coloring of an amazing sketch, The elegance of the wings now greatly enhanced by the colors. The celestial mane has the ghostly feel without the lines from the sketch. The coloring is superb. ^.^
The colors and shapes are all awesome, but it seems the outlines could use some smoothing. Maybe using a less coarse setting on the aibrush for the mane might be a good idea. What program did you use for this one, anyhow?