As it was requested by a commenter in the first icon post, I have made a tutorial for you all! This one focuses solely on coloring; the following tutorials will be centered around painting backgrounds, unusual coloring styles, applying textures, how to write a letter to your congressman, working with poor-quality scans, and different layer effects. I hope you'll find them helpful!

For this tutorial, we'll be going from this...



...to this:



Please note that the tutorial is fairly long and image-heavy.



This was all done using Adobe Photoshop Elements 6 and a Wacom Bamboo Fun tablet. You could do this with a mouse, but it will be very, very difficult (I should know: I used a mouse for my first icons). So far as other programs are concerned, any newer edition of Photoshop will work, as will Paint Shop Pro. I don't know very much about other programs, unfortunately, but as this tutorial is simple I imagine it'll work for them, as well.

Moving on--I typically use preprepared bases for icons, as they often don't require any cleaning or fixing. This came from jlarinda:


Note the screen tone above Sakura's left shoulder. You should try to make the line art as clean as possible--no matter how much you like the screen tone! It's possible to use it to one's benefit, but more often than not it will badly affect your colors. This is more relevant to series like TSUBASA RESERVoir CHRoNiCLE, where screen tones are prevalent. We'll be looking into that in depth in a later tutorial; for now, let's just erase that wayward blotch.



Now, make a new layer above the base layer and set it to "multiply." Start painting in Sakura's hair, making sure to stay within the lines (this is where mouse-users begin to weep). I chose this image of Sakura as a reference for what color to use.



Once you've painted in all of her hair, lock the layer by clicking on the symbol circled in green here:



(It'll be slightly different depending on what version of Photoshop you're using, but you'll be able to recognize it.) Now, you'll only be able to paint on what you've already painted--meaning, you won't be able to paint outside the lines. Unfortunately, I'm fairly sure that this function is limited to Photoshop, so those using other programs will have to continue being careful with where they paint. (EDIT: The lock function also exists in Paint Shop Pro. Thanks to light_flower for the information!)

That said, paint in the shadows of Sakura's hair, continuing to check the reference picture to see what color to use. It's not particularly relevant here, but make sure to paint them according to the light source (something which, again, we'll be looking into in future tutorials).



Next, paint in the highlights. In order to blend the colors well, alt-click on the image to pick up colors as you paint. This will be more difficult for if you're using a computer mouse--try the smudge and blur tools, instead.



Make a new layer, set it to "multiply," and begin painting in Sakura's skin. (You may want to start naming your layers at this point, if you have difficulty keeping track of such things.) The process of painting the skin is basically the same as painting the hair: set down the base color, lock the layer, then add in shadows and highlights. Checking the reference image and properly blending your colors is very important here!



Paint in Sakura's eyes. Take note of the duller color I used--far too often, I've seen otherwise pleasant icons of Sakura marred by toxic-green eyes. All versions of her. Seriously, please use a more subdued shade of green.

Also, remember the shadow cast by her upper eyelid and eyelashes.



Add in some yellow-green for the highlights...



...brighter green for the middle of the irises, and a more brownish color for the shadows. Painting an eye should be much, much more complicated than this, but this is Card Captor Sakura--where no one has muscles or fingernails, and only those over the age of fifteen have noses!



Make a new layer directly above the base layer and set it to "screen." Fill it with a dark brown--I used #332b28, which is rather dull, but you can use a warmer shade if you like.



Now, on the same layer, paint over the lines of Sakura's hair with a color slightly darker than the one you used for the shadows of the hair. Experiment with different levels of brightness to get the effect you want.



Go over the eyebrows with a reddish-brown, and the pupils of the eyes with a dull, dark green. Make a new layer on top of all the others, set it to "normal," and add in stray highlights and...those strange blots of light that seem to plague most of CLAMP's artwork. Maybe they're pieces of stray magic, or something. I don't know.



Make a new layer just below the layer with the stray highlights and set it to "multiply." Paint in the wand and the star on Sakura's hat; I used this image as a reference.



This is very much the same as painting in the hair and the skin: lock the layer, add in shadows...



...add in highlights. You know, I think I've been working on this tutorial for over four hours.



Paint in Sakura's hat, the trim on her dress, and the star beneath her wand.



Add in more shadows (note the shadow cast on Sakura's collar by her wand).



Go back to the layer set to "screen," and paint in some dark teal over those parts of Sakura's dress that are hit with the light. You may not be able to see this step, depending on your monitor settings, but it makes a difference!



On the same layer, lighten the lines of the stars and the wand using a color slightly darker than their respective shadows--as you did with Sakura's hair.



We've almost reached the end!

Going back to the layer on top of all the others, add in more tears in space-time caused by one magician's wish to save his beautiful assistant white blots. Also add some highlights to the tears in Sakura's right eye.



Make a new layer on top of all of the others and set it to "exclusion." Fill it with a dark blue--I used #00111c. If you use a blue closer to teal, the image will take on a pink hue; if you use one closer to violet, it will take on a yellow hue. Likewise, the lighter the blue, the more pronounced the effect. Again, experiment to get whatever effect you like.



We could stop here, but the icon looks somewhat boring. Let's damn fidelity to the source material and make the tassel pink, using the screen layer.



And that's it! If you have any questions, or if you see any mistakes, please feel free to contact me. Also, if you used this tutorial, please comment with your results! I would like very much to see them.