I'm trying to work on moving past 8x8 pixel characters. I like the blocky look, but there isn't enough room for detail. I'm working on some concepts for a Steampunk-themed game, but my skills are quite lacking. I'd like some advice on how to keep the blocky design (I'm using 16x32 px, doubled for the final version), but get the shading right. Here's what I have so far:
I think when people begin attempting shading the biggest mistake they make is to shade each little part equally and individually, when each part
should be shaded differently from each to convey a sense of cohesive depth between the separate parts.
What I mean is: figure out how each part of the object is to be shaded in relation to each other, THEN think about how to shade each individual part. And don't be afraid to have one parts not shaded at all, maybe if it's in the shadows or something.
Here's an example that should make what I mean obvious:
Here's a bumpy sphere.

The first image is unshaded. The second is poor shading, like how beginners often shade, because each little section is shaded individually without thought to how it fits with the rest. The third is shaded better, because the shading is mostly concerned with giving it an overall shape, and THEN there are subtle alterations to each section to make it look slightly raised. Obviously it was done quickly and only to make a point so the shading isn't the best, but I think it's good enough to get the idea across.
And here's an example with a character I quickly sprited.

Notice how #3 has more logical depth and a more logical shape to it than #2. The light source in number #2 is "consistent" in that it always comes from the right, but it doesn't make sense if you consider the person to be a 3d shape.
This is a concept that I didn't understand well for a long while, so I hope this helps. I think that I made it clear enough, but if I didn't feel free to ask questions.