I modeled the head poly by poly, using images as reference, just to have a good base mesh with nice loops. I started by the nose, after that I jump to the eyes, mouth, then chin, jaw, ears and finally I close the back of head. So basic this is my workflow for the head, when I have this base mesh done, I beginning to tweak the proportions and work with the sculpt tools for give me the look I want.
For the eyes I used two separete spheres, and then I modeling the cornea, iris and pupil. Also I modeled the eyelashes, instead of using hair, for this, I used small cylinders and was just duplicating and tweaking. You could do this using the front image of your reference applied into your model, just do a projection from view at front view, this way you have the position of your eyelashes in the texture, then you just need to position your cylinders. I learn this trick in a cool book of Ballistic called The Face.
To make the textures of Ruby I used the images of Liliana, from 3D.sk. First, I used the texture paint, using the UV mapping project from view and painting the images of the front and side views into the mesh, so we have a base texture on the main uv, which was created before. After this I go to GIMP and started working on the diffuse texture, copy and paste the good parts of the textures to improve some bad areas. I almost don’t use the clone stamp because if you are not really good with this, it’s easy to screw up your texture. When the texture is done, I use the sharpen filter for give me some fine details. I worked with 4k images for the diffuse and bump maps and other maps with 2k.
To make the skin shader I created a material node with four SSS layers and two other for specularity, this is really heavy and will increase your render time a lot. The four SSS layers are for the overall color, epidermal, subdermal and back scatter and the two other are for the soft and hard specularity. Also I used one more SSS shader in the eyes, this will give a lot of realism to your eyes.
The hair was made in Blender, with hair particles. I used the children method simple, this way you have more control, because the childrens will follow exactly the hair particle. You could also grab the particles and put where you want, because it’s linked to the particles, just uncheck the Root option in tool bar, press G and move to where ever you want, but don’t forget to check again the root option in tool bar. Then start to comb and tweak.
For the lighting I wanted give to Ruby a calm and soft look, so I did a illumination more diffuse. For this I used two spot lights at front of her, one spot at the back as back light and one more spot turned to background for create some kind of bloom effect at the background. There is one trick I used in lighting, I created two big planes and linked to the two front spots, then I create a white material with Emitter setup to 1.5 for the planes. So this way you have some fake reflections like area lights, you could see this in the eyes.
The compositing I made was simple, I just rendered three passes, z depth, specular and ambient occlusion. First I adjust the contrast and saturation, then I ajust the specular and ambient occlusion. After this I applied effects like Glare and Defocus. There is some tricks I used, one is use z depth map to control the background separate without render another layer, for this just connect the z pass in the factor of any node. The ColorRamp I used to control and adjust the maps like ambient occlusion or z depth.