No personal attacks; while criticising the work of other contributors is fine, personal attacks and insults regarding their race, sex, creed etc. are unacceptable.
Some principles of Wikipedia etiquette ("Wikipetiquette")
Limit and qualify your statement. Blanket statements or statements asserting the truth of opinions can inflame the reader, and sometimes if you identify it as your own personal point of view, it can help make it seem less insulting to those who disagree.
Acknowledge that you understand the other point of view, by showing yourself able to restate it fairly.
Avoid writing on topics you are overly passionate about.
Finally, As a Last Resort, when you've tried to work in a cooperative spirit and are not getting through, NPOV find w:WEMA
How to avoid abuse of Talk pages
We are editing each others' work, and when working on political and other incendiary topics, inevitably, a lot of the edits reflect our personal biases. Very often, political disagreements are interpreted as personal insults, or attacks on our intelligence, dignity, cherished values, or honesty. Egos can get wounded and concomitant attacks and defensiveness are all too natural. So, the talk pages are there--and are used to duke it out verbally.
The basic purpose of the talk pages is to help improve the article to which the talk page is attached.
Wikipedia is not a debate forum--that's not what it's designed for. If you want to debate, there exist more appropriate venues such as Usenet, public weblogs and other wikis.
The fact that someone disagrees with you does not mean that (1) the person hates you, (2) the person thinks you're stupid, (3) the person is stupid, (4) the person is evil, etc. There are many things you can falsely infer from the fact that someone disagrees with you. It is best not to infer anything at all along those lines, and let that person live with his or her own opinion in peace.
Before adding a comment to a talk page, ask yourself:
Is this really necessary? Why can't I simply edit the article with a summary and leave it at that? Won't it be obvious what I've done and why?
Will I actually succeed in changing any minds? If not, what point does the discussion have, given that the purpose of Wikipedia is to create encyclopedia articles?
Am I adding this comment simply because I want to defend my ego and advance my own cause?
If I really want to continue this debate, is it of general interest, or would it be better to take it to e-mail?
Efficiency often requires silence.
So let's please, please conscientiously avoid trying to use Wikipedia as a place where partisan controversies can be settled.
The controversies do bring some people back to Wikipedia, perhaps--but it's equally reasonable to say that they also turn off a lot of other people, the sort of people who don't ever engage in such controversies. You should also bear in mind that Wikipedia is extremely exciting quite apart from the controversies--exciting enough all by itself to keep us coming back.
It seems we have wasted hundreds of hours, altogether, engaged in pointless debates that we could have avoided with tact, maturity, and attention to the task at hand. We could have been rather further along than we are now, perhaps with more participants, as well. If we can start a good anti-partisan-bickering habit now, then, in the years ahead, future Wikipedians will thank us for it.
One habit that would be good for folks to get into is to actively seek to summarize discussions, especially those which have elaborated all views on the subject.
Avoid bias. Articles should be written from a neutral point of view, which means that articles should represent differing views on a subject fairly and sympathetically.
Wikipedia is an encyclopedia. The site should primarily be used for developing the encyclopedia. In particular, the facility to upload files should only be used for files used in articles, and discussions on talk pages should be directed at improving articles. See what Wikipedia is not.
Respect other contributors. Wikipedia contributors come from many different countries and cultures, and have widely different views. By treating others with respect we are able to cooperate effectively in building an encyclopedia. For some guidelines, see Etiquette.
Follow conventions. By following these conventions we are able to produce a more consistent and usable encyclopedia:
Deleting useful content. It's impolite and counter-productive to simply delete content that is useful just because it is somewhat biased (why not just remove the bias?) or because it's poorly copyedited (why not do the necessary copyediting?). Except in the very most obvious of cases, deleting anything over, say, a few sentences demands some words of justification on a talk page. A good principle is never to reduce the overall amount of useful content in an article.
Treating Wikipedia as a chat forum. On talk pages, it is all too easy to get involved in emotional, partisan debates about various topics. Unless this results in an improved article, which it often doesn't, for drawn-out, emotional squabbles, please just sit on your hands. There are many other places online where you can engage in debate and to try to persuade other people of your views. That's really not appropriate on Wikipedia, because we're trying to focus on the task of creating an encyclopedia. Please see What Wikipedia is not.
Thinking that there is an "author" of any given article you read. A common misconception of new arrivals to Wikipedia is that there are single authors of articles. This leads people to issue critiques on Talk: pages when they could just as easily make changes to articles themselves. The fact of the matter though is that no article here has just one official author, even if only one person has worked on it. Anyone can work on any article, and if you see a problem with an article, and you can fix it, then please do fix it then and there. Don't bother with the Talk: page unless politeness demands you explain what you've changed (it often doesn't), or that you ask a question first. For more information, see Be bold in updating pages and Talk page.
Adopting a combative stance. Some new people immediately see that there is a special community of people here committed to working together toward friendly consensus. Others make the mistake of treating disputes on Wikipedia as on a par with Usenet-like flame wars. Most old hands want to spend as little as possible time in nasty, competitive disputes. That isn't what Wikipedia is about. There are acrimonious disputes, even among the old hands. We ain't perfect. But it does seem safe to say that most of us aren't here for that, and we are embarrassed and frustrated when it comes to that. We're here to write an encyclopedia. For that, some amount of Wikipetiquette (if you will) is required. See also Staying cool when the editing gets hot
What wikipedia is not
Propagandaoradvocacy of any kind. (But an article can of course report objectively on what advocates say, as long as an attempt is made to approach a neutral point of view. Go to Usenet if you want to convince people of the merits of your favorite views--and good luck.)
