Because clients can present very different interfaces, it's difficult to point to a single guide, but the basic principles are simple enough: get a client, point it at a server ( https://www.eternal-september.org/ provides a free one if your ISP no longer has its own, but it doesn't carry the alt.binaries subhierarchy), download the list of available groups, subscribe to a few, read, and enjoy.

As for which client, I use Pan, but that's Linux-specific. For other OSs, I haven't a clue. If you happen to use Thunderbird for email, I think it still has the necessary support.

Keep in mind, though: USENET died in part from lack of good moderation options, so all you can do about bad actors and spam floods is block messages from those posters from being visible in your client. Moderated groups did exist, but the system basically amounted to one person having to okay every single message posted, which meant there was a single point of failure. For instance, when the moderator of rec.arts.anime.info died unexpectedly, it became impossible for anyone to post to the group.

90% of the news hierarchy is a wasteland these days anyway—I use it mostly for monitoring some of the mailing lists from my Linux distro, which happen to have a USENET repeater. The only other area doing well is the binaries groups.

If you're interested in running a server, start by making sure you have a good-sized data pipe—I'm not sure what the average size of a feed is now, but ten years ago it was measured in the tens of gigabytes per day (mostly binaries).