These are variations of a character design for a mascot, that was designed, among others, for an exhibition appearence.
Based on the different versions, the client who commissioned the character was able to decide which aspects of each character he liked and wanted to see included in the final result.
I made the choice to use flat coloring with downplayed shading for this character.
This might be interesting for you as well:
On of the roles of the composition of an image is to depict the most important elements of the picture in a clear, recognizable manner. For color pictures, not only the placement of the elements is playing a central role, but the color composition as well.
An obvious method is to separate diffrent elements or layers within the image like foreground and background by different color saturations of a difference in lightness.
There are many approaches for setting up a color composition. To acquire some helpful rules of thumb, it can be useful to look at some of the oldest works of visual design in history: Coat of arms and flags.