Finally - a question about something concerning which I actually know something!
http://www.ibiblio.org/usenet-i/usenet-help.html is a pretty good tutorial for starters.
Here are a few suggestions I would make.
1 Get a good NNTP-feed.
If you are interested in groups carrying binary files, alt.binaries.whatever, a commercial provider is your best bet, and
http://www.giganews.com is among the best there is, offering a variety of plans at reasonable cost. Using a pay service is critical for binary groups, as only the commercail services have the completion and retention needed to make binary newsgroups worthwhile - there is little more frustrating thatn finding that your Usenet feed has 97 parts of a 100-part file you are downloading.
2.If you are only interested in text newsgroups, then
http://news.individual.net/ (my prime feed), is an excellent choice. Run by Berlin University, it offers over 23,000 newsgroups and good retention of articles. This means that, once your newsreader is setup, you can search for groups that are likely to interest you and be reasonably confident of finding them.
3.LURK. The dynamics of each Usenet newsgroup are different, so I would recommend a minimum of a week, preferrably a fortnight or so, of silent lurking, reading posts, getting a feel for who's who in the group, what subjects are considered ok, that sort of thing. It's also a good idea to use Google groups to do a search of the newsgroup for previous threads that may have addressed any questions you wish to raise. In almost every newsgroup you will hear the mantra, "Google is your friend", or its less civil equivalents.
4ENJOY. Approached carefully, Usenet is a fantastic resource, and buckets of fun.
A word of caution regarding posting from Google groups - it is viewed with suspicion and disadain in many newsgroups, as it is a favoured approach of spammers and trolls. I use Google groups extensively for searching group archives but almost never post from Google.
And, finally, don't listen to naysayers who say that Usenet is past its best. Yes, it's clogged with spam, but so is email. It's still a great resource, and there are some outstanding communities of interest. It is still very worthwhile.
Usenet
