I'd like to make a suggestion. Three, actually.
1. More focus on "DO"s than "DON'T"s. Most roleplay guides are very specific--some too specific--about what's frowned upon. Most are very vague about what SHOULD be done by comparison. And if they aren't, they usually oversimplify things.
For instance, many place too much importance on the idea that "details=depth" over the idea that relevant details equal depth.
Or they ignore that formula and stock character types aren't bad and that building a "complex" character isn't about avoiding them so much as mixing the basics well.
My problem with this is that I think it helps cause a lack of posting. People recognize the stuff that everybody rails against, but it's not uncommon that many of us claim to lack good ideas or perceive our writing as worse than it is.
I think people need to be reminded to draw from what inspires them. To look at what works just as often, if not more so, than they cringe at what they're told doesn't work.
2.Acknowledging that there is a time and place for cutting lose and writing whatever comes to mind. Sometimes it's just too easy to slip into a constant "must prove I'm not stupid by not writing stupid things" mentality.
3.Discussing situational issues like hijacking and godmoding. When is it okay?(MIA player? You're the GM?) When isn't it? What are preferable alternatives? (e.g. Collaborating through PMs and messanger discussions or just asking other players for permission.)
When I first started roleplaying, I found it horribly confusing that everyone claimed to hate hijacking yet there were certain people who seemed to get away with it and be praised for it even. Of course, I understand now, and I'm actually conditionally pro-hijacking, but I think it would be convenient to address things like this realistically instead of pretending no one likes it and that no one ever gets away with it.
Those are my three cent. ^_^