The Housemouse stamps from Stampendous remain a favorite for practicing any type of coloring. The images are so detailed that the design illustrator has already done most of the shading, or at least given guidelines as to where to add darker tones.
For my cards today, I stamped Monica and Friend / Bird Feeder with versafine onyx black then embossed the image with clear embossing powder. The embossing forms a bit of a barrier to keep color from bleeding out where I don’t want it. I used Zig clean color Real Brush markers and a very small waterbrush to blend out the color.