Below are some of the tutorials I have written, currently all for an obscure piece of gaming software called Nolimits 2.

Nolimits 2 (tunnels part 1): Global texture coordinates

Learn how to use texture coordinate generation for terrain-covering objects like trenches and tunnels

Nolimits 2 (materials part 4): Specular maps

how to make good specular maps and when to use them

Nolimits 2 (materials part 3): Emission maps

access additional material registers using the NL2 custom shader core

Nolimits 2 (materials part 2): Texture sizing

How to choose sensible texture sizes for Nolimits 2 projects

Nolimits 2 (materials part 1): The specular model

How specular lighting works and how to select realistic values for your materials