Note: I won’t give color swatches on this, nor will I tell you exactly what to do. This is my general way of doing things and you should just use it as an example to learn off of. It’s my belief that people learn from seeing a pattern, rather than by being told what to do step by step. I hope that this tutorial teaches you a few things that will help you formulate your own patterns and gain experience in color. Good luck, bon chance, ganbatte kudasai, and enjoy!
-Mirolan

Step 1: sketch and draw, ink (optional), scan.	Step 1.
Step 2: Edit the lineart. This is a long one, sorry. X_x Open the drawing in Photoshop. If needed, you should adjust the brightness/contrast so that the lines are as dark as possible, and the background is white. After this, you may choose to edit mistakes that were possibly made with inking, or erase any pencil lines that might have been left behind. The easiest way to do this is with the paintbrush tool set to the color you need. Make sure your lineart is black and white, with no definite color, before moving on from this. Once the lineart is completed to your satisfaction, duplicate the layer from the background layer to a new one, and white-out the background layer. Select the channels menu and hit the load channel as selection button. This should select all of your lines. After this, hit the delete button on the keyboard, making sure you’re on the layer with the lineart. After doing so, deselect the lineart, hit the lock transparency checkbox, and color in the lines with black. You can just use a large brush and sweep it over the image.	Step 2.
Step 3: Base color. And finally, we move onto the fun stuff! We’re gonna start by creating about 5 or 6 new layers. Generally when I color, I use different layers for each different area of color, but for slower systems, it might be a good idea to group different areas together. But, anyways. I generally start with the physical features – skin, hair, eyes, any feature that can’t be changed for the character. (After all, you can match your clothes to your skin, but it doesn’t work the other way around, ne?) And thus, we begin. If your lines are solid and enclose the area completely, you can just select the area with the magic wand tool . This doesn’t select all of the area, though, so go to select > modify > expand, and use a value of about, say, 2 pixels, maybe? If that isn’t enough, you can fill in empty spots in a minute. Okay, so you’ve got the area selected. Now, after you choose a color to fill it with, hit the paint bucket tool and fill in the selection. An easier (but slightly messy) way (this is what’s shown) is to simply choose a larger-sized brush from the paintbrush option, and wipe it across the area for color. This works well for the face, especially if the character has long hair, because the area will be filled over in another layer.	Step 3.
Step 4: Choose a light source. In real life, you will most likely never encounter a setting where you only have one light source. But we’re talking physics here, and in an ideal world, you could only focus on one light source. Just, y’know, pick a spot for the light to come from. ^^; I usually put some sort of marker in that area because I easily forget. (^^;;;)	Step 4.
Step 5: Mimicking the cel style. This is immensely easier with a tablet. It can be done with the polygonal lasso tool as well, though. Or even with a mouse, but unless you’re really good, it might not work out as well. So either with the polygonal lasso or with the paintbrush set to a small, hard brush size (I generally use the “hard round size 3” brush for this), outline the area to fill with shadows. This is where you need to think about light and shadow. Where does light fall on the face? How does that affect shadows on the face? A few things that you might want to keep in mind: shadows follow forms. If the form is straight and vertical, you won’t have very much of a curve in the shadows and highlights. If the form’s curved, like a sphere, then you won’t get very straight shadows. Simple as that. Also, the strongest point of shadow won’t be at the edge of a form, but by the edge of the shadow. So anyways, pick a darker, deeper shade of the color to fill in with shadow. Make sure it isn’t too dark or it’ll stand out too much. On the flip side, if it’s too light, it’ll be hard to see. This is also the basic form for highlights. Highlights, though, will generally be smaller areas, and they generally lie strongest near the edge of shadows. Confused? Look at your forearm in the light of a strong lamp. Pay attention to the deepest part of the shadow and the strongest part of the highlights.	Steps 5 and 6.
Step 6: Deeper shadows. This is totally optional, but it helps give an image more depth. On the other hand, most anime cels use one layer of light, and one of shadows. But we’re not making anime cels, are we? ^^ Again, it’s much easier with the tablet (if you’re using a tablet, turn the brush dynamics to stylus), but it can be done with an alternate measure. Basically what we’re gonna do is put a smaller area of an even darker shadow inside of the main shadow, to follow the contours of the shadow and the shape. It’s done basically the same way as the other shadows, so I won’t go too far in depth.
Step 7: Continuing the color invasion. The other layers are done basically the same way. Hair is probably the most difficult, because, while shadow falls mostly on the side opposite the light, it also falls within the body of the hair. There will be a lot of shadow by the neck on both sides of the head. Remember with hair that it’s not delicate and smooth all the time. Adding a second layer of shadow in the hair can, again, add a lot more depth and make the hair look more…well, hair-like.	Step 7.
Step 8: The eyes. I saved the eyes for last for a few reasons. Firstly, they’re done a bit differently than the rest of the body. Second, well, they’re just more fun. ^^; So here’s what I do, listen if you want. Since I usually don’t draw and ink the eyes in, I take the time now to draw the circular orbs, using the color that they are. After doing this, I create a new layer above the lineart layer and create a glossy shine in the eye. This follows the usual light source, but the shadow is a bit different. After the eyes are nice and shiny, I return to the main eye layer and lock the transparency. Then, get a darker version of the base to use as a main shadow. You can also use black to create more of a contrast, but that comes eventually anyways. ^^; So, start by adding a shadow under the gloss. Then, add the darker part of the eye (there’s a technical term for it, but...yeah), and shadow at the bottom/sides of the eye. After that, if you want, you can use the dodge tool to make the eye shiny.	Step 8.

Finished image: version 1.
Finished image with background.

And that’s generally how it’s done…my way, at least. Use these techniques to your advantage, and I hope you learned a few tricks along the way. Good luck!