Hey everyone. I’m a novice when it comes to modeling/texturing in Blender right now. I’ve watched a few YouTube videos tutorials on how to work with materials and textures in the node editor and I’ve got the gist of how to work with the UI and add in nodes and such. As it stands, however, I don’t really understand the function of all the nodes or how they work together to create some of the amazing renders I’ve seen from Blender. As far as my real-world application goes, I’m interested in modeling out game objects that can be exported and used in game engines like Unity. What are some tools you guys would recommend to help get a grasp on how the material node editor works (books/videos/other websites/etc). I know a lot of the knowledge comes from just general work within the editor and figuring out the nodes for myself; however, any help/advice you could throw my way would be appreciated. 
the best way to start would be the manual:
https://www.blender.org/manual/pt/render/cycles/nodes/index.html
Looking at the osl implementation of the cycle’s nodes, can give you lots of insights on how to use nodes to do allmost everything you may need, specially the textures.