Circles are Google+’s way of helping users organize people in their network. You can have a circle for friends (the kind you know in “real life”), co-workers, family, etc. You can create circles however you want to. Circles make it easy to share information with the people who would be most interested in it. You can post your vacation plans to Family and information about a new conference to Co-workers.
What trips people up is that people can add you to one of their circles without you authorizing it. You get a notice that they’ve added you, so it’s not like it’s totally anonymous. People who are more accustomed to Facebook than Twitter tend to get confused by this. “Who is this person and why did they add me?” Well, they might have seen a post you made to Public or that was shared by someone in your Circles. They might have seen you in the list of “Suggestions” (people who Google thinks you might have something in common with).
You do NOT need to reciprocate if you don’t want to. If Bob adds you to one of his Circles and you don’t add him to one of yours, the only posts of yours he will see are things you post to Public (or Extended Circles, if he’s in a circle of someone in your circle). You will not see his posts in your regular Stream. You can see his posts if you click “Incoming.”
Here’s the conundrum people find themselves in: They want to have a large network, but they don’t want the posts of a gajillion people cluttering up their Stream. Let’s say you have a topic that you tend to post about, perhaps the Civil War. You want to reach as many people with an interest in the Civil War, but you don’t necessarily want all their posts coming in. (Let’s face it — there are some people who post everything to Public, even though “Public” really doesn’t care about the lunch they just ate.)
So how do you build a large network of people in a specific topic that you want to send to, but you don’t necessarily want to follow them? My solution:
Two separate Circles.
Create one Circle for topic and another Circle for topic – not following.
Going back to the Civil War example, you’d have a Circle for Civil War. This would be all the people you want to send Civil War-related posts and you want to read their posts, too. Your other Circle would be Civil War – not following. Here would be the people you want to send Civil War-related posts, but you do NOT want to read their posts on a regular basis.
When you post something related to the Civil War, send to both of those Circles.
How does this help? You can narrow your Stream by circle. To read the good stuff about the Civil War (or, at least, those people you think typically post good Civil War stuff), click on Civil War.
You should occasionally look at your topic – not following Circle to see if there’s any good stuff there. Maybe someone there has figured out that “Public” doesn’t want to see pictures of their kid’s hamsters 🙂
Amy's Genealogy, etc. Blog 
Good tips Lori!
Thanks for this. I have just started using Google+, and this helped.
I’m glad it helped! Have fun with Google+! With the recent changes on Facebook, there has been a great influx of new users. Exciting times ahead, I’m sure!