Not sure how easy this is to organise on the forum admin side, but I understand that it is possible to have Topic Templates on a per category basis.
Given the way that a fair proportion of new forum users often overlook the level of detail that’s necessary for anyone to have even the vaguest chance to help them, I thought this might be a positive and proactive way to nudge them towards doing the right thing (or possibly make them realise this may end up being beyond their commitment level before they jump in blindly)
The basic details of Topic Templates for Discourse are described here:
I signed up to the Demo site for Discourse (linked to from page link above), and when you go to create a topic which is in the “Movies” category, it pre-populates some details.
As you’ll see, someone else has asked whether comments that don’t flow into the final post are possible, and it does seem they are - I confirmed that HTML formatted comments do not show in the final submitted topic post, so I think the trick is to create the guidance comments wholly or largely as HTML comments and then even if someone’s a complete beginner at forums / the internet and doesn’t realise unneeded template text shouldn’t part of their submission, it won’t leave the entries littered with this kind of mildly embarrassing artefact 
Any template needn’t be super complex or onerous - could start with a basic mention of the guidelines and a word of encouragement to point people in the right direction. It can always be extended / altered / removed later depending on how it goes.
My motivation here is to bring some harmony between groups
- On the one hand, the more experienced find it frustrating when people haven’t been practical (and I am sympathetic)
- And on the other, the beginners seem to struggle to express themselves with relevant details (esp given some skip/miss seeing the guidelines).
Beginners may still skip things but I’m hoping it’ll be marginally less likely and even a few fewer cases would be better than none!!
Any thoughts on this?