Many questions by new users end up closed as duplicates or for another reason related to the lack of familiarity with the site. I won't go into details; they are much discussed. 

I propose to enable an [interstitial how-to-ask page](http://math.stackexchange.com/questions/ask/advice): it is automatically shown to new users after they click "Ask Question" button. The page gives a few bits of advice: 

* search before asking (it conveniently includes a large search box)
* make sure you are stating a clear question with some context of where it came from. 

This page is already enabled on some other high-traffic sites (Stack Overflow and Server Fault among them), but not yet here.