Since I get this question pretty often, I'm going to go through the brushes I use for my digital inking and also go through the process of a piece from start to finish.
First off, the brushes. I usually only stick to 2 main brushes and use a mix of scratchboard and inking techniques. The first is just the plain old standard round brush which I use for all the drawing and detailing. The second is the round bristle brush in cs5 which I use for most of the crosshatching, texturing and shading.
One big thing to remember though is that the brushes are only half of it. The other half is getting into the Scratchboard/Inking state of mind. The trick to this is to be constantly switching between drawing with black and also white, pulling out the lights, pushing back the darks, and just playing with the values until you get a look or texture that you like.
It'll be easier to see and explain in the process shots.
Here's the first stage to any piece, the rough sketch. I noticed since middle school I just default to drawing Batmen since it's so fun, it just happens naturally and I can just shut off my brain and draw.
A plain profile shot against a solid black background felt too boring, so I threw down some rain lines.
At this point you want to start blocking out the main light and dark values, but you also want to play around and experiment as much as you want. Later on you can decide what elements you want to develop and and what parts you're just going to blot out. So it's pretty much a free for all.
Plus, towards the end it'll be easier to see what works and what doesn't.
Around this point I realized if I'm going to have him in the rain I should work in some water flowing down his mask, also it'll add an extra element for you eye to follow.
It's important at these early stages to start thinking what kind of flow your piece will have.
Here I'm just fleshing out the face and the mask and playing around with the water and splashes. Its starting to become a dance between making it too busy/overworked or plain/boring.
This stage is more clean up. Smoothing out the shadows and blacking out any stray marks that I feel don't add anything to the piece.
It's also important not to smooth everything out too much. You want to keep some of the freshness and spontaneity from the original sketch. It'll go a long way to making the piece feel alive.
Around this point I hit a wall. I kept working and working it. But it still was't looking how I wanted.
Moments like these are pretty common and I've always found that the worst thing you can do is to try and muscle through. You'll only end up frustrated or even worse, you'll ruin the piece. The best trick is to flip the image horizontally to see it in a new light or take a break to come back with fresh eyes. I did both and it did't work. So I used another trick.
I lasso tooled the jaw and mouth and started distorting it and playing with the proportions. Sometimes you have to listen to your instincts ad trust your eyes. I knew something was off, but it wasn't until I started moving things around that I finally saw that his face was too long.
And here we're at the final stages at last. I waited till the end to overlay some rain on top because you don't want to overload your eyes while your working with a piece thats too busy.
And here's the final piece after some tweaking, smoothing and lots of second guessing.
All in all, I hope this process helps some of you to play around. I realize the way I work is very messy and unorganized. And it's not for everyone, because it's even tough on me sometimes. Each layer and each stroke is a gamble. I look back on all these step and find myself wondering "Is the water too distracting? Is the rain on top too busy? Would the composition be stronger if the head was blacked out? etc, etc." In fact I almost prefer the version without the overlaid rain and water.
But, in the end you can listen to these little voices and always have doubts, or you can say "fuck it.", keep working, move forward and don't look back.
Because in the end, your choices are what makes your pieces unique.