This question was made and I asked the usual:
You should provide more info: What have you tried? What are the definitions? What book are you reading?
The user replied me by saying that he tried to do something about it - but he was unable to understand. I tried to help by suggesting some heuristics that could be interesting in posing questions but I believe that the competence of guiding people on how to make useful/interesting questions is lacking in me.
When I was new in the site, I remember of not having the skill to isolate my problem in a precise way - I'm not a professional at it today, but I believe I got a little better with time.
So is there a official guide made by MSE to help people to formulate their questions a little better? If this guide does not exist, shouldn't we make it? For the time being I guess I should suggest this webpage on Math Overflow. Although the MO guide seems to be complete:
It's not official on MSE;
Some users shouldn't even know about the existence of MO. I guess it's counter intuitive to think about searching for how to make a nice question in another website, we can't expect them to think: I want to make a good question, I'll search the technique for it on MO!
We would have to repost the link for every new question that isn't following the given criteria. As it is the case with the PSQ's - the community should always repeat: Welcome to MSE! Do not post PSQ's! Live long and prosper!