Here we will group advice and some guidelines for new users on how to write posts, behave properly and interact with other users.
If you wish to use this guide on another SE site, you can, but please let us know and remember to give attribution!
Some points I'd thought I'd add:
The guideline of not being aggressive might be argued for slightly differently. Some posters may actually enjoy an attack--counterattack style of discourse, but aggressive writing will repel most site participants, and in general tends to drive female participants away from participating. If you take issue with another member's comments, voice your dissent in a way that showcases your tactfulness.
For citations, we should emphasize that citations are suggested especially when potentially unfamiliar or non-standard terminology is employed. Since it is not possible to anticipate which terms will be unfamiliar to readers, it is appreciated if the OP will edit the post on request to include citations for highly specialized or non-standard terms.
On this website, attacks are done by proxy. Instead of saying, "That idea sounds, wrong, here are some reasons why" people instead say "so and so (Chomsky, Daniel Everett, K. David Harrison, Ruhlen) is a crackpot". [Not saying crackpots don't exist, just saying a lot of flaming of people with Ph.d's going on] I would say attacks by proxy are just as problematic as attacking the OP, the answers, etc.
First of all, consider looking at these links:
Always include context, details, background. There is a question body so you can elaborate on the "title/question" in order to be more specific and clear about what you're asking. Providing info, not only reduces the risk of down-voting or close-voting, but it also improves the chances of having a proper answer. The better the question, the better the answers!
Write appropriately and use the correct formatting. This means use capitals letters and punctuation when it's required, also use the blockquotes for quotes and not the code-field, which exists to write code. Avoid slang or colloquial expressions as much as possible. A well-written question/answer is one of the steps of attracting better answers or upvotes too. Also, avoid writing a huge single paragraph. Five small paragraphs are more readable than a huge single one.
Avoid writing links like "this" or "here". This is not a strict rule, but it gives people the chance to know what they are going to visit, or if it's a site/pdf/image. For example you might choose a wording where the text-link is the title of the document you're linking; it's also useful if you specify when it's an image, for those who have slow connections.
If possible, include a reference. StackExchange sites are about definite, objective answers and not about opinions, (that's why we have the "subjective question" close-vote), so providing reference, you're assuring the OP and the readers that what you say is true and backed up.
Avoid one-line answers. It might be correct, but an answer made by a single sentence is not that informative. A bit of elaboration is very useful for the reader and for the visitors. Don't worry about being "long": every information you think that can be useful for the others to know will always be accepted.
Be kind to other users. If you're writing a question, remember that you're asking to be helped, so make sure to show your appreciation to the ones who answer by being kind. If you're answering, instead, don't attack the OP and don't be aggressive; this doesn't mean you can't question/challenge other answers or the question. The point is that being tactful would help to face the discussion in a smoother and better way. It won't bring any good to the site to just attack other people, especially being personal. Like they say "treat others as you wish to be treated".
Citations. When you cite a paper/article, don't just post a raw link. Please provide the title and the author(s). For example: "Title" by [author]. You get the idea. Providing citation is also useful in case the subject is not widely known. But we encourage citations regardless of the subject being famous.