Coloring manga scans: a mega-guide

For starters, I apologize for any mistakes, I'm tired as all hell after proofreading it 4 times and can't spot them anyway. I'd be really thankful if you point them out when you see them c: And leave comments! RAWR.

I can't count the times when I came across an image that I really liked and wanted to use, only to be stopped by it being black & white. Since I didn't know how to color or clean it, I was reduced to staring at it and cursing whichever author/magazine decided to leave it b&w or fill it with text. Then I thought: hey, I mostly read and work with obscure manga, so there's little to no chance of those images being cleaned or colored.
After numerous trial and error moments and experimenting with colors and vectoring, I was able to clean and use those images, instead of being forced to mumble under my breath and craft voodoo dolls (that I totally never ended up using).

And here it is: a guide for coloring manga scans!

Even though I re-used some parts from older tutorials, I updated the examples and "theory" to fit this one :) You should still check the tutorials I point out, though, as some things are treated more in-depth there (not like I was too lazy to write them again here, but this thing is long enough as it is ^^"). So I recommend taking a peek at them if you can.

This guide was written with Photoshop CS5, but will work for other versions since there're no Earth-shattering differences between them. I don't know about other programs, though, since I use only PS; if you use others, you will need to see which terms here fit your program's commands. I should also note that I don't color big manga scans anymore (I work exclusively with icons nowadays), but this won't get in the way of the explanations.

Of course, feel free to ask questions and discuss! And tell me if you think I missed something or would like me to elaborate on some points :)

Table of contents:
Step 1: find your scan! + Optional step: positioning the scan
Step 2: cleaning the scan - simple and advanced scan cleaning
Step 3: let's color the damn thing already! <-- warning: HUGE Wall O' Text (TM)
Step 4: checking for mistakes
Parting words + related tutorials + image credits

Abbreviations and terms:
b&w = black and white images
base (image) = the image you want to color; once I open it up in PS, I normally name it "base" to distinguish it from the other layers
BM = layer blending mode
lineart = the outline of the character(s)/object(s) featured in the image
raster layers = normal layers, on which brushes and paths (created with the "Paths" option of the Pen Tool) can be used together; they become pixelated upon enlarging
shape layers = layers created when using the "Shape Layers" option of the Pen Tool; they do not lose their sharp quality upon enlarging and are very useful for quick color changes, selecting etc.; basic component of vector images