Sprite shading tutorial
Giving your creations a colorful look is a difficult process for the beginner. Sprite art is tricky to shade properly if you don't know what you're doing. This is the difference between a hobbyist, a newbie, and a professional: Most will use extremely different forms of sprite shading. It's take hours to cover all the possible pixel art coloring techniques in-depth.
Here are brief descriptions of several of the main types of sprite shading for graphics. You can find many examples online if you look around. These three are typically used in games and animated series.
In one word: Don't do it! This is typically where the inside of an object is brighter than the rest, and you make it darker in colors the deeper it goes and along the outlines. It looks horrible unless all the other pillow shade sprites are the same style. Even then, it doesn't look all that good!
This is typically when your sprites have dark black edges. The inside colors also have outlines, and usually only have two or three different shades in their associated parts. It looks a lot like what you'd find on a cheaply animated cartoon. However, unlike pillow shading, sprites with comic shading do look quite good if everything matches the style.
This is the most difficult, and most effective type of sprite shading to pull off. Generally speaking: Your outlines are all a somewhat darker color of the other on the sprite in that area. For example, someone in blue pants. Their outlines would be dark blue. You then shade all the inner pieces with lighter colors as if sun was shining in a direction, typically north west.
Pro tip: It is with natural shading that other colors make a large difference. Purples are fantastic for shadows. Using light green helps add a vibrant "alive" mood to the sprite graphics.