This is a great idea. Basically so far we have a great friendly community with generally good feedback and critic, but it never hurts to have a nice guideline for it. Would you be willing to write such a guideline?, I am sure there would be a shiny badge for doing such a thing.
I'll preface this by saying I'm relatively fresh to the concept of online forums (I used to, it turned sour, I left); however, I'm also keenly aware of the critiquing process as a seasoned writer and general creator.
If you would like me to, I'd be more than willing to write a post on "critiquing guidelines" (badge or no badge :3). I'd send you a copy of it before posting, as well as I would ask where the best place to post it would be. I don't imagine it'll take more than 24hrs to develop - the weekend is upon us, after all!
This is something that did not exist in previous forums I was a part of, and it resulted in many regulars inexplicably tearing apart people's work. Lots of creativity shot down, lots of nasty comments and hate left behind, many beginners giving up before they got very far. I don't want that to take over here, ever. If you would like me to compose a draft, let me know. ^u^