I see a lot of suggestions offered, but the best one would be 'Before' the questions/discussion/document are even submitted. Based on keywords on subject/content, there should be closely associated articles popped up in something like a 'Have you seen this before?' section/pop-up which will give some generic suggestions on what can be done like
*Search with Keywords, e.g. on good searches in the community, and
*Closely related articles in the context etc based on keywords
I believe this would help the sanitize the community for the better like avoiding duplicate questions etc
I am sure there are more ideas that can be added into this area.