I decided I'd try my hand at a tutorial thingy, not just a simple progress report as I've been doing with Felysial. This is my first time, so I may suck at it. The biggest problem I have is getting ahead of myself and forgetting to stop at a point I probably should have.
First off, you'll note I haven't shaded anything in this sketch. Most artists
do, but I don't like to. I do all my shading with color. Shading it with pencil
first just gets in my way of applying tonal and value colors.
1. Scan in the pencil sketch. Darken the darks and lighten the lights with the
Image>Adjust>Contrast command . Then, with the Magic Wand tool, select
the whites, then Select>Inverse, to capture just the pencil outline. I had
my Wand setting set to 20 so I could collect as much line as possible. Copy
the pencil outline and paste it into a new window. I titled the outline layer
"outline". I did this because I want to put in my own Photoshopped
background and I didn't want the sketch itself to be the background layer.
2. Created a new layer and titled it "body". Then I colored in a quick flesh tone in this layer so I could easily see what was body and what was background. I made sure I left a hint of the outline so I could still see it.

3. I decided my main light source is off to the viewer's right. I threw in some
rough shadows and highlights to indicate this. I will eventually have another
more subtle light source in the background, but I'll worry about that later.

4. Added more definition to the body. Darkened the darks. Started erasing some
of the outline lines on the outline layer. Also started correcting some minor
mistakes I had in the drawing.

5. I tend to jump around a lot, so bear with me. I got tired of the body, and
went to working on the face, or more specifically, the closest eye to the viewer.
I added a new layer and labeled it "face".
When doing eyes, remember that they are basically spheres. If you ever took art lessons, one of the basics you should have learned is how to shade a sphere. The most intense highlight is found coming from where the light source is coming from. On the opposite side of the highlight, light reflects inside the iris because it is semitransparent. The far inner corner of the eye is the darkest. The eyelid also casts a small shadow onto the eyeball.

6. I've started slapping on some color around the eye and have erased some more
of the outline on the outline layer. Note the pink line of color below the eyeball
and above the lower lid. A lot of people forget about this important piece of
the eye. It's essential to making an eye look real. Gotta have them tear ducts!

7. Ok, this is one of those big jumps I was referring to in the beginning. I
should have shown a step or two before this. Got carried away... Anywho, all
I did was color in the whole face in flesh tone, then started to add in the
shadows. Note that the right side of the face (the dark half, away from the
viewer) is deeply shaded, including the eye. Always keep your light source in
mind. It helps to think of the face as a series of basic shapes, such as spheres,
incline planes and elipses. The nose, for example, is basically a cylinder with
planes shaved off on each side.

8. More detail on the eye. I wanted to point out some particular details: Always
use many colors when shading flesh. Skin actually picks up all kinds of colors.
In the deepest darks, I used greens, purples, blues and browns. I rarely use
just black. Black is a very flat color, or more precisely, it's the absence
of color, which is not the case at all with flesh tones. Even the pupil is a
mixture of deep purple and black. Another detail I added is tiny dark purple
lines in the iris itself. I'm not sure why these lines exist, but it's how iris'
look. Makes the eye more realistic.

9. Jumped down to the mouth now. Filled it in with some basic color and erased
the outline.

10. Application of deeper darks and lighter lights. Note the upper lip is mostly
cast in shadow. This shows how the upper lip recedes into the mouth, while the
lower lip extends outwards from the mouth. Also keeping in mind the direction
of our main light source by shading the portion furthest from the viewer.

11. Here's a detail of progress on the mouth. Note the little wrinkle lines
on the lower lip. This was done using the finest/smallest setting of my airbrush
tool. First I'd draw in the dark line, then right beside it, to the viewer's
left, I drew a lighter line next to it. This gives the effect of a darkened
crease. I also airbrushed in finer points of highlights and shading in between
the creases for added realism.

12. More work on the face. Darkened the shadows by adding more browns and blues.
Gives a more sinister feeling to the face. Added a highlight to the cheek bone
and a bit between the chin and the side of the jawbone closest to the viewer.

13. Started to work on the headband. Here's where layers become very important.
The head band consists of three layers: The gem, the gem setting and the tentacle
bands. I actually wish I put each tentacle on it's own layer. It would have
made shading them much easier, but c'est la vie. Putting the headband on a separate
layer makes it really easy to shade and color the flesh behind it.
For the gem, I basically cheated. I used a real photo of a gem in some copyright free stock photography that I have. All I had to do was enlarge it and put it into the right perspective. I have a Photoshop plugin called "Andromeda" that manipulates an object so you can turn it on several axis to easily achieve the perspective that you want.
For the setting, all I did was create an oval with the Marquis tool and then used a filter from Alien Skin called "Chrome". Then I added my own shading.
For now, I just threw down some color for the tentacles bands. I made them three different shades of gray so I could tell them apart.

14. Now we see some highlights and shading on the tentacle bands. This was all
done by hand. If I had placed each tentacle band on it's own layer, it would
have been easier for me to shade them.

15. Completed the headband, for the most part. There's always the constant tweaking.
: )
I started working on the "hair". At this stage, it's part of the face
layer, since I wanted it to look connected to the head. I haven't decided if
I like this look. Right now it's kind of a "sprouting" look. I may
try a more blended look, going from flesh tone to black. This would make it
look like the flesh transforms into alien flesh. Now, it's as if the tentacles
are a separate entity that has popped out through the skin. Both concepts are
equally creepy, but I may default it to the more aesthetically pleasing.

16. OK, here's hair-tentacle option number 2. I may go with one. Needs more
development, obviously, but I like the gist. The only problem I see with this
version are people mistaking them for dreadlocks. The above version is unmistakable
as something alien. I'll have to ponder both versions for a while...
Again, note the use of many colors, not just black and shades of gray. Now I'll place the remaining hair on a new layer to keep from messing up what I've done so far.

17. Yeah, I'm goin' with hair option #2. With the proper application of squishy
snake-like lighting, I can achieve a tentacle look, rather than a dreadlocks
look. Kinda scary how well this came out. It's almost as if I've seen the real
thing. Yeah... almost just like it... >: )
Anywho, I got a lot of work ahead of me with all those tentacles. The basic steps are, first fill them all in with black, then go over them with a very dark purple and gradually build up with lighter and thinner streaks of purple where the light would hit it most. Then add the burnt sienna closest to where it touches the skin to indicate the flesh tone reflecting onto it. Then, I go back to the body or face layer and add any appropriate shadows that would be cast onto the skin.

18. More progress on the hair and I colored in the ear. I looked at my own ear
in the mirror as a model, but I probably shouldn't have. My ears are really
small.

19. I thought this was a good point to stop and make a point. : )
As I'm chugging along with the progress on the hair-tentacles, I started to
develop a better technique as a I went along. Very annoying when that happens,
cause then I have to go back and do over what I've already worked on. Originally,
I planned on coloring the tentacles furthest away from the viewer (your left,
her right) to be reflecting all sorts of colors because I plan on putting some
tentacled monstrosity in the background which will have all those colors in
it. However, I like the way they came out so much, that now I think I need to
go back over the ones with just the purple and orange highlights (closest to
the viewer), and do the same technique. They just look so much cooler! I have
a close up below:
Note all the perty colors in the "cool" tentacles! : )

20. Filled in all the tentacles and laid in some very subtle colors. I'm going
to leave them be for now and work on other aspects of the image before I complete
them. Since I'm not 100% sure what I'm doing for the background, I'm not 100%
sure what colors should be reflecting off of the tentacles in the back.