There are lot of different people meeting and talking in newsgroups; it is seen as some kind of courtesy to obey some rules of manner, the basics of which are listed here.
Before you ask questions be sure you have read the newsgroup's FAQ (Frequently Asked Questions) and didn't find the answer.
If you take part in a discussion be aware of the fact that everybody can read the answer: do not say anything that you would not say to the others if you were facing them; avoid insults.
Try to avoid crossposting: do not ask a question in more than one newsgroup when you do not know which is the right one. Ask in one newsgroup; if it is wrong, you will be told which is right one.
Formulate your articles accurately; nobody likes to read an article with lots of typos, even with content worth a Pulitzer. Think of your articles as letters: your letter speaks for you; it represents you; somebody reading your article will draw conclusions about you from it, wrong or right.
Remember, nobody sees your grin when you are writing an ironic sentence: it may be funny for you, but it can be very serious for the person reading it. It is very difficult to include emotions in an article.
The most important rule: use your common sense when you are answering or publishing an article.