What this post is actually about is, with people from Tumblr joining in droves: How does one get a Dreamwidth reading page that's full of interesting people writing interesting things? I started answering this on gallusrostromegalus's introductory post, but I figured it might be useful more widely.
I'd also like to hear other people's thoughts on the matter in comments -- this is just me tossing out some ideas for things that have worked for me, but I've had pretty narrow experience mostly from years ago, and fandom changes quickly sometimes.
Anyway, with that said, here's what I had to say in the comment:
I mostly found interesting people by commenting on other people's posts (which, unlike Tumblr, stays on their post rather than being a separate post on your page) and then following other people who made interesting comments on people's posts. That means there can be an advantage to going back and looking at older posts -- usually from the last day or so; things seem to taper off a bit after that unless a really interesting conversation starts -- to see if there are new comments. Also, if an interesting conversation starts or a post looks likely to spawn interesting conversation, you can click the "track this button" (which looks like a little bell in my default style; I'm not sure how universal that is) to get notifications when people make new comments on it.
Unlike Tumblr or Twitter, there isn't really any way to see all the comments that a specific person is making -- but you can see their "reading" page using a link like http://brooksmoses.dreamwidth.com/read (or click the "reading" link on their main journal page) to get an idea of what the people they're subscribed to post. That won't include private posts that you couldn't otherwise see, and if they use a lot of circles to have specific narrower reading pages it won't show you what those are, but it is still pretty useful in finding other interesting people.
Finally, on things I have actual experience with: I'd note that my friend jenett does weekly "salon" posts which are basically just forums for people to have conversations in the comments. The most recent one is at https://jenett.dreamwidth.org/1794110.html, to give you an idea -- and you could either join the conversation there if it looks interesting and looks like a group of people you want to join, or you and other people reading this could start your own if the idea looks useful but there's less community overlap.
On things I don't have experience with, Dreamwidth also has communities, which are essentially communal journals where multiple people can post -- those were a big thing in fandom in the LiveJournal days and I believe still are here now, but it's been a long time since I've had time to seek those out. There are also the "interests" lists in people's profiles, which become links to lists of other people with that interest listed.
 Yes, this proclamation on their part led to creation of at least one community where people are posting things like a photo of a naked nipple with two eyes and a very distinctive mustache inked onto the surrounding (rather large) breast to make a cheery face. Obviously.
Crossposted from Dreamwidth (original here), with comments. Comment here or there; comments here will eventually be duplicated to there.