Hey check out this video : https://www.youtube.com/watch?v=AvOQYUjAw_Q - Physical based Rendering - A practical Workflow for 3D Artists- Featuring Substance painter.
you should check out: Gnomon Workshop, Practical Light and Color - Theory and Application with Jeremy Vickery if you havent. it helped me a great deal.
This is SO me! Yeah I'll try to get to speed stuff. But somehow I feel that speed stuff are not portfolio worthy. Is it? Maybe just for learning/practice.
Generally it's better to simply paint in full color, but that requires more practice. Colorizing grayscale is OK, but IMO the end results tend to look flatter, not as dynamic.