Like with every skill you just need a little time and some dedication to get good at something. I just always looked at what I had, thought about what I can do to make it better and tried.. that's all.
Over some time you get a precise feel and taste for these things.

But seriously, I'm not THAT good and I'm lacking a lot of knowledge when it comes to certain shader-things (shadows, just to name one of them).

I don't think I have what it takes to make shade-c better... man, I don't even understand how shade-c exactly works.