For a new person, I'd suggest subscribing to a handful of users right away -- I'll list a few below, they have public feeds and you don't need to register for the service to check 'em out -- and then get into the group for new users. The community is pretty supportive. There are certain very popular users I would suggest not subscribing to right away, or making sure you put them in a list so they don't overwhelm your main feed. Lists are your friend.
My Suggestions for First Follows:
I'm following about 250 people, this is just a handful of names that leapt to mind, but I could've easily rattled off several more.
There are a few super-users that it's sort of de rigueur to follow, but I recommend corralling so your feed doesn't get hammered.
Alex Scoble - his brother is apparently famous in tech circles, and Alex is certainly famous on FF. He gets tweaked a bit by other power-users for his opinions and, if you're into drama, I think you'll get exposed to as much as you might want through his interactions with them. If you follow and don't assign him to a list, you're feed will be a Scoble-blitzkrieg.
Louis Gray - probably needs no introduction. Famous IT blogger. Like me, he's a father of twins. Fathers of twins know what's up.
There's a cadre of cultists and trolls of various stripes, just like you'll find on any service: christians, libertarians, fanbois, Republicans, tree-huggers, what have you ... you (or I?!) may be one or of them, so you'll either fit right in or be able to tell pretty quickly who's ... well, to be blunt ... too stupid to talk to.
Finally, here's why I prefer FF to other social media sites:
- I hate that Google Buzz is in my Gmail. It looks like shit and I have no patience for it. It offers nothing to me beyond what I was already doing just fine in Google Reader: discovery, sharing, commenting, and saving for later. I have no idea why people like Buzz, frankly. But, people do, so there must be something there I'm missing.
- Facebook is for my friends and family. I don't share publicly and want to keep it that way. Plus the UI is horrible. And I don't play the games and don't want to know what games anyone else is playing or what they need help with.
- Twitter is fine. I like it quite a bit. But you can't have a conversation there, it's full of spam, people tweet too much, and I'm verbose so 140 characters is a bit restricting. It's also failing all the time. (Friendfeed, as I mentioned above has its own issues, but at least I can consistently check the site and post the way I like.)
- Orkut ... well, Google is just all over the place aren't they? Nobody I know uses Orkut (one guy, actually, but he doesn't use it much either) so I don't get anything out of it.
- Amplify, Lazyfeed, and a few others I'm forgetting have some good features but nothing that made me want to switch away from FF. I might use one of them more if FF perishes, but not until then.
There's a Friendfeed widget with my recent activity at the bottom, you can scope it out without even leaving this page.