CUTTING:
Photoshop 6.0

Cutting is a method that comic book colourists (like Liquid! from such fame as Battle Chasers) use when CG'ing their pages. It's fairly simple. You just lay down your flats, add shadows, and then 'cut' your highlights.

Open a new document at 200x200 pixels and 72dpi. Let's fill this in with a nice dark blue colour (R:0, G:0, B:80). Some people like to use the absolute darkest colour possible, and let the cuts do all the highlights. I like to use the middle colour, then use a gradient or my airbrush to add the shades, and then add highlights with my cuts. You get different effects going either way. Experiment.

Okay, now we have our really boring blue square. Let's establish a light source first.

Let's just put it in the upper right hand corner. That's normally where I work from anyways unless the light source is pre-established by the penciller and inker. Now let's add some shading. All I did was grab my airbrush set to 'multiply' and brush so that I gave the sqaure at least a little depth to it. Don't forget, shading can be done with all sort of colours. Skin is the hardest element to shade. If you take the original skin colour and just try to shade it set to multiply only, then it comes out too burnt looking sometimes. Try grabbing a different colour to shade. Pardon the mega dithering and banding on the example, but you get the general idea. I just put the white border around so you could tell the difference between the background of my page and the actual example.

Still boring? I know. Now comes the fun and difficult part. Cutting. Basically what you do it you take either the Freehand Lasso tool, the Pen tool, or the Freehand Pen Tool.
If you are a mouse user, I recommend using the Pen tool because you can have greater control over your cuts, but it will take you about 10 times as long to do a picture. If you don't know how to use the Pen tool, Designs By Mark has a great tutorial on how the Pen tool works.
If you have greater control with your mouse than I assume you do, try the Freehand Pen tool. You draw your selection freehand, and then it will smoothen out for you afterwards. You can still see the vector points and you will be able to move those around as you need too afterwards.
If you're a tablet user (ie: me) use the freehand lasso tool. If you want to be really precise then you can go right ahead and use the pen tools, but by using the Freehand Lasso you can work really really fast.

Make a selection like so...

You can hide the marching any selection by pressing ctrl+h. I always do because I can see the edges of the selection easier, but for now I won't so you can see what I'm doing. Then grab your airbrush tool. Some people prefer the paintbrush, but as far as highlights go, i like the softness that I can get from the airbursh. Using the same blue colour, set the airbursh to 'screen' and then brush over the selection.

Now go back to your selection tool and 'cut' around the original area.

Repeat the step with the airbrush brushing over the selected area. If you deselect the image (ctrl+d) you can see how after adding the 2nd cut and brushing over it, the entire area progressively gets lighter. All you have to do now is keep repeating that same method until you have a nice gradual highlight.

If you look at the final pic, you can see how it gradually goes from light to dark in steps. There are ways to get your steps to appear less evident, but that's something you have to develop on your own. Now go try this out on some lineart. If you find you're having trouble, try taking the tutorial over again until you understand how the cut works. Once you understand how it works, then you can manipulate it and do other things and make it bend at your every will, or something like that.

Good luck and have fun with the tutorial. I really hope it helps you out because I get lots of e-mails asking me what a 'cut' is. If you're still having problems and you still can't seem to grasp the concept, drop me a line or post in the BBS. There are some really great colourists that post in there often enough along with myself so you can get a feel for several different styles.