We've already had a few questions come up where people have asked 'How do I make xyz material/texture?'
Do these questions count as tutorial-requests, and thus should be considered off-topic?
These questions, by their nature, seem to invite too much discussion (especially when either the word 'realistic' or 'best' is in the question). But I could reasonably see questions of this type being limited enough in scope that there is no concern.
I imagine that, if we allow this kind of question, it will be a very popular, especially among new users.