Quote - I give people shaders that have plenty of knobs to turn for different results and there is NO MATH in doing that. Yet only a handful pay attention to that. If you want to build a little bit, you can do that too. You want a clouds node in your BBGlossy diffuse color? Plug one in.

Yup, I spotted all the user-parameters... in your recent shaders BB, usually all over to the far left, left of the main node, I think?

I've certainly managed changing colours, textures... adding my own bump etc... and indeed even adapting the black painted wood shader to make the "Police Public Call Box" sign on the TARDIS, in my last render.

I managed to add the original image_map texture with the sign graphic on it, so that it was driving a blend node, between the black background (made of the black painted wood) and white text, with the white being made out of the lit lamp shader (with brightness turned down a bit).

I do feel like I am getting somewhere by playing around like that...

...but as I say I think I personally learn better by trying to dissect fully formed examples, rather than buiding step by step from scratch. Although going through the latter process likely builds a more thorough understanding I guess.

The Castle Poser tuts look like a worthwhile read... thanks for the link.