Making of Halloween Witch by Amber Chen, Georgia Web: www.kagaminoir.com


Base Colors

Next I laid down the basic layers as well as colors for the painting. These layers go under the line art.  Generally, I choose a dark base for most things except for skin, which I start with a light midtone.  (I did start the orange parts with a midtone at first, but I later changed that while I was shading.)  I made a new layer for each color, and some colors even have two layers for easier separation of parts. Otherwise, it was just a matter of using a hard-edged brush to fill in the colors.  I set the background to varying gray tones as well to help me see whether I had painted each color all the way to the lines (dark gray for light colors and light gray for dark colors), and while I did my best the first time around, this is easy to touch up later.



Shading

Finally it's time to give this painting some depth!  Currently, the main brush I use to paint with is a custom round brush with jagged edges.  I set both opacity and flow to pressure and turn up the angle jitter to maximum.  You can try this yourself, but of course you should always use whatever you're most comfortable with!  
There are a few ways to easily paint each section. I used to use "preserve transparency" on each base layer.  This allows you to paint only where already is paint in that layer.

Alternatively, you could create layer masks of the base layer--either on the base itself or on new layers--to constrain your paint.

However, I have relatively recently discovered a new love: clipping masks.  The keyboard shortcut is ctrl/cmd+alt+g (and it's in the Layer menu in the top toolbar too).  It's like a layer mask, but the mask is automatically set to the base layer below it.  You can also have as many clipping mask layers as you wish.  (The next one you make is set to the same base layer as the first, not to the first clipping mask.)  Clipping masks make any touchups of the base layer very simple.  If you find that you missed a spot, just fill it in on the base layer, and the clipping masks automatically fill in as well without your need to manually redo the masks.
I like to start painting with the skin, especially the face.  It's important when you're painting (and I do this even during my sketching sometimes) to flip your canvas horizontally occasionally while you work.  This makes it very easy to spot mistakes, as most people tend to skew their art either to the left or to the right.  If it looks strange, fix it while it's flipped, flip it back, and fix it again if you need to.  This is particularly noticeable when it comes to the face, so when I'm working on a face, I mirror the canvas relatively often.  Photoshop does not have this command set to a shortcut by default, so I made one myself.




Even when I'm concentrating on the face and skin, though, I still like to rough in other areas bit by bit.  It gives me an idea of how the image will look as a whole so I don't lose sight of the forest for the trees, if you will.