Smooth-shading Demonstration

I have gotten a few questions about how I do my smoothshading, so I thought I'd put up this demonstration (I wouldn't call it a tutorial...it's not extensive enough for that). There really isn't much to it, except using a tablet and putting in a lot of work.

Note: A digital drawing tablet will be extremely helpful in preventing you from going insane. If you're serious about doing digital arts - get one. However, you can do this with just the mouse - it will just take longer, since you need to put the brush opacity really low, and make many passes before it starts to produce results. If you need advice about digital drawing tablets, read my recommendations here.

I did this in openCanvas, but it can be done with just about any painting software.

If you don't have a suitable project to try on, grab any old sketch or line art drawing you have and start shading. Here I am using a loose sketch of a surreal Mini Cooper.
 

The line art (or sketch) should be in its own layer. The same goes for the background and the flat colors. Lock those layers - you don't want to mess them up by accident. Make a new layer for the shading. It doesn't matter if you use an ambient light color in a multiple layer, or hand picked colors in a normal layer - the same technique applies.

Now I select a blur brush with a radical blur strength. I go over the shading to even it out a bit. You can see the result to the left. But while it looks a lot better already, it's still very untight. Notice how the blur brush has washed out the shadows along hard edges (like the bottom of the door and around the fenders). This means we have to paint some shadow back in.

Stage Three:

If you look closely at the image to the left, you'll notice that I've filled in the shadows in several places. I used a soft brush for it.

If it turns out you've painted in too much and cannot undo it, just use a soft eraser brush and carefully dab with the stylus over the affected areas.

Now that we have repaired the shadows, we need to go over the image with the blur brush again.

I chose a smaller blur brush this time, with a moderate blur strength. Be aware that I haven't gone over the entire vehicle with it - just the select areas that needed smoothing out.

Here I have gone back to filling in the shadows and carefully dabbing the eraser over certain areas. It's starting to look like something doesn't it?

This is the essence of the workflow that I use for shading and highlighting. I go between the paint brush, the eraser brush and the blur brush, and just keep at it until I'm satisfied.

As you can see, this vehicle needs plenty more work, but it's definitely going in the right direction. =)

Apart from the colors (in their own layer under the shading) I've also started adding orange highlighting from overhead street lights. It is still far from finished though.

Btw, for reference; The shading was done with a light greyish blue in a multiple layer, and the highlights with a saturated orange in an addition layer.