I’ve made your old post a wiki, Tamas, but I agree with @ctkelley — guidance to students is more a question for the course professors/TAs. I don’t know that our guidance to students needs to be any different from Please read: make it easier to help you. The one exception in my mind would be that I’d like to encourage students to be honest up-front that it’s a homework problem.
That said:
The bigger question in my mind is how we suggest (or if we need to have explicit suggestions for) our existing members respond to obvious homework prompts — either explicitly labeled or not. Personally I like SO’s suggestions on this front: How do I ask and answer homework questions? - Meta Stack Overflow.