I've come across people who need a good start in digital illustration but been unable to explain it clearly (we artist tend to be more visual) so I made a cheat sheet for anyone who needs to refure to it.
Now, there's TONS of methods out there but this is the culmination of information I've found to get great illustrations made quickly.
So here's a quick breakdown of the layers:
1: line-work; quick and fast, actually based on a rough not shown here, usually contains the darkest of shadows and holding lines. Alternatives to using RICH BLACK (as black is rarely found in nature) can be blacks with trace amounts of grey, blue or violet
2: Shadows; as a rule, shadows are blue in natural (yellow) sunlight (or shift toward blue, sometimes their purple based on some tutorials I've seen but are usually the color absent of ambient light). Use this layer as midtones.
3: Ambience: The color used to display lighting/mood of an image, the color that ties conflicting colors together (in real life this would be similar to paper color or tone). Possibly interchangeable with shadows depending on how intense the shadows need to be.
4: Color: these are "base" colors (or colors that somehow maintain in any environment), works close in conjunction with ambience OR can work WITHOUT ambience provided it follows a fairly rigid color theory palette (eg: this image generally follows a secondary color palette with the exception of blue, which is quickly subdued/shifted to "fit in" as seen in the last toothman).
NEVER use colors at 100% saturation unless it's used to direct attention (even then, super saturated colors generally are obnoxious)
For any questions, feel free to ask or feel free to download for study/teaching " )