It's 100% bad.Used the base color as a mound of clay and did the outlining at last (Do point me out if this is a bad way to do things/practice , Which it might actually be).
Sketch -> Outline -> Coloring
The way I do it is sketch with a green color (Bright, very visible), then lower the opacity to 50% and outline it black.
Some people want the outline to be gentler (not black, so a darker shade of the color), but that's easily fixable by making a child layer of the outline and painting it with the chosen color.
Once the outline is done, you can disable the sketch and do the coloring (use magic wand to select the areas, then expand by the width of the outline - 1).
Once you have the coloring (Each element should be a layer imho), you can do the shading and other stuff on child layers so you won't risk them going out of the bounds.