This is copied from the tutorial I'm posting. May as well educate as many people as possible. :-)
I'm more or less working on one section at a time here, bringing each one to "almost done" (or maybe done, we'll see how it all ties together). So his head is pretty much done, but I'll probably be doing a little more work on bringing out some texture. What you see there on the neck is kinda like a base coat. I usually put in whatever will be the lightest tone, over the whole section, and then go back and darken as needed. It takes a few passes to get it dark enough. I showed that in the bear tutorial, I can do that here too. So I'm not making any particular effort to finish a section before posting these pics, this is just how far I got today.
And a closeup too! I'm trying to really pay attention to whether I make the dots the same size, and I've have to say for the most part I do. It's only on the lightest areas that I lighten up on the pressure (it hardly takes any, especially here, this stuff is pretty soft). But honestly it's so subtle it really isn't that obvious. I primarily achieve tonal variation by varying the density of the dots, and somewhat by varying their depth.
That brown ink's looking pretty good, eh? ;-)