Anime Head - Roareye Black
Before the tutorial starts, a brief note. This is a modelling workshop and as such, it will not show how to make one specific art piece, but instead pose different bodyparts from different angles using different techniques. As such, the work will be unshaded to show the structure of the work, and it will be up to you to practice this knowledge and apply it to your own artwork.

This tutorial is focussed on the structure of the head. I have included a picture of an actual anime head and added bright colourful lines to show where the curvature of the framework should be added. I'd suggest having that pasted into your canvas at the side so you can see the curvatures more clearly. For ease, I'm going to use the same colours on the pixel art head in this tutorial so you find it easier to follow. Your starting point should be to make a red circle on your canvas, which is the main size of the head.

Next, make an oval beside your circle in the light purple. This oval should be taller rather than wider. It should be roughly one and a half times the size of your original circle.
Now depending on which way you want to make your character face, take the side of the oval facing that direction. So I want this character to face to screen left, so I'll take the left half of the oval as my base. Then place it in the centre of the face, this is the centreline of your head and it helps judge where the rest of the face goes.

For the rest of the facial features, we need guidelines to help tell us exactly where we are and what we're doing. So you need to make another oval, this time wider rather than taller, which is roughly half the height of the circle and a third (1/3) wider. Alot of this is based on your own judgement of these measurements.
You only need one half of this oval as well, so it really depends on which way your character will be facing. If it's looking at eye level or lower, then you want the lower half of the oval, if they're looking upwards towards the sky then you want the upper half. I'm going for an eye level view, so I'll take the bottom half. Once you have taken your half of the oval, you now need to copy it and paste it in twice. Now take into consideration that these two lines are where the eyes are, as well all know Anime eyes come in various sizes but are usually large. With that in mind I've left a large gap between my lines. Also these eyes have been placed in the centre of the circle because of my character's positioning. If your character was looking up or down, you'd move these two lines up or down accordingly.

Now you can clean up your wireframe a bit, repairing the red of your circle before continuing. Now you can see the structure a bit more easily. Your next step from here is to create the ear, which is a Hot Pink colour on the example image at Step One. Because of colour similarities, I've instead made it a sky blue so it's easier to see. To create the ear you need to make the top begin moving round and upwards before bringing it back down and then slimming it to the face. This is more based on your own ability than wireframing.
Then move the ear into the head. Don't attach it onto the side of the circle, because your character will look wrong. If you look at the example picture again, alot of the bottom half of the circle is cut away later on, and the judgement of this has alot to do with the placing of the ear. So you need to place it slightly inside the circle but it still needs to break the circle's outline, as seen above.

You need to now remove the purple vertical curve from the circle but only in the lower section of the head. This isn't necessary, but it makes the image clearer. Now follow the purple curve to it's centre, where it bulges out the furthest and then follow that down in a straight line and place a green dot below the bottom of the circle. How far down depends on the size of the circle, however I'd say it needs to be only a fraction below the circle's underside. This is something you'll have to judge, as it determines the length of your character's chin.
Now make another oval which is taller than it is wide in the blue colour (See example image for where this curve will sit). You need to decide for yourself just how much curve you want to take off of the face, remembering that I'm only going to be using the top right corner of the oval (The corner you use depends on the angle of the face) for this to work.

Now you need to place the curve on the face. Judge the height of the circle you want to take off, which is dependant on the character's facial type. If it's a cuter or female character then you want to dent the circle higher for a rounder cheekbone, if it's a slimmer faced character, you want to dent the cheek lower for a slimmer cheekline. I'm going to make a slimmer faced character so I'm denting into the face at a lower point.
This is a good time to clean up your wireframe so you again get a better view of what you're doing.

Your next step is to create the cheeks. Using the Curve tool (Shown in the Technical tutorials - MS Paint Tools) draw a straight line from the bottom of the ear to the dark green dot you made earlier. Now click outside the circle to make the line bend into a curve, and make a small, subtle curve in the line. Then click the Select Tool to prevent any further clicks from ruining the curve.
Again, reselct the Curve tool and click at the dark green dot this time, and draw a line to the blue curve to the bottom purple eyeline. Then move outside the circle and mould the curve again. Once you have it perfect, reselect the Select Tool to prevent any clicks messing it up.

You're entering the final step of the basic wireframe. All we need to actually sort out in terms of modelling now is the position of the neck. With this in mind, we follow the yellow line on that example image. Create a yellow (I've used gold cos it's easier to see) oval that is taller than it is wide, and is thinner than the red circle, but ever so slightly taller than it.
Now take the side that will be showing the neck curve. In my shot it will be the top left of the oval, which part of the oval you use depends on your angle of course. This doesn't have to be touching the rest of the wireframe, since the finished product would not follow the headline exactly either, and this is just a guideline. You've now finished your wireframe.

Now simply draw in the facial details. I'm not going to add loads to this, as it's an example copy, however for some help, the nose should be small and delicate and placed just below the lowest purple eye marker and there should be roughly an equal distance between the nose and lips to the lips and chin. Smoothen off the modelling so it's less jagged.
Now recolour all but the bright purple tones as black, you can use the Rubber Tool trick to do this. Keep the bright purple markers for any editting work until completion and also so you know the centre of the forehead for when you make the hair.

Now you can just colour it and add hair and the other features as needed. However of you this is entirely up to you, just remember to make the hair and any headwear follow the light purple guidance lines before removing them. I havn't added many features of perfected the detail in this face because it's an example image, so it's best not to leave it in the state I've left it in. Finish up with shading and full-on facial features.

Another example of the head using this tutorial. Notice how the head looks completely different due to the positioning of the 'Blue' curve at the other side of the head.