Before you send out a question, search to see if it has already been addressed by the group. Learn about the community of people, their concerns, their tolerance level before you solicit information from them. And don't overdo it. When Jerry Garcia died, a message was posted by a journalist to the rec.music.gdead newsgroup, asking for stories or memories anyone would like to share, information about local vigils, etc. You can read the posts here.
People are upset.
Take small bites, find a few good places, monitor them well, and gradually build up your skills, gradually get this technique for covering your beat incorporated into your style of work. Most newsgroup lists and finders will indicate whether or not a newsgroup is moderated. This is truly unfiltered information and should be used carefully. Depending on the kind of story you are doing, this can be a great source. When rumors were rampant about an errant military jet pilot who disappeared over Colorado, newsgroups were a great place to go to read the crazy theories for a story on, well, crazy theories.