Yesterday I've applied for the Mastering Modelling in Blender workshop, organized by CGCookie.com.
Although I have been able to model whatever I need, it is always good to know from the specialists how to do things in the proper way, to save time and to improve your skills.
Meanwhile, I've been also looking into Open Shading Language, which is a new tool in Blender that allows the creation of more flexible materials. Here is a .blend file with some of the materials I've found and one that I created myself. I'm preparing a second one, different from what I've seen, and I'll post it here as soon as it is finished.