And now for part 2 of my hand painting workflow, here’s part 1 if you missed it.
Use a BIIIiiiig brush to paint a global gradient from light to dark, top to bottom.
Use a smaller brush to paint downward facing surfaces darker and upward facing surfaces lighter.
After that use a smaller brush still and lightly define some ceases with dark and edges with light color.
At this stage you can also very lightly paint in some ambient occlusion in creases and corners.
Now that the shape has been defined, I sometimes map down some macro detail as well as a reference for when I take to painting the detailed texture in Photoshop.