Everyone has their own individual style on social media. Here is mine, in a nutshell, for whatever it may be worth to you:
First, my life is an open book, so virtually everything I post is public. The other reason I do this is because I think I have a message to deliver, and I want to be able to broadcast it effectively to a large audience.
For circle management, I really only have two main circles -- "friends" - which is where everyone goes initially, and "close friends", which is a circle you earn your way into. More on this in a bit.
When somebody circles me (which happens anywhere between 10 and 20 times a day), if time permits, I check your profile. A complete profile, with a photo of a real person, and at least a couple of posts so I can figure you out, will generally get me to circle you back.
To get into my "close friends" circle - which is the only one I am really interested in, because that is the only one of my circles that has the notifications feature turned on all the way, you need to meet the following general criteria:
1) You need to make posts. People who are inactive or who post rarely hold no interest for me.
2) You need to be an "engager" - That means not only that I see you interact with people on your own posts, but you also actively seek out and interact with people on their posts.
3) You need to be unique in some way - post original or interesting content, engaging, thoughtful content, commentary, etc.
4) I need to see that you are honest, ethical, and sincere. People who I find out are dishonest, who lie, who are hypocrites, or who hurt others in any way are quickly dumped - as they should be. This includes people who I have gotten close with who later turn out to betray me.
For the remaining people who earn their way into my "close friends" circle, which now numbers about 70 and which I'd like to take up to 100 or so, I am fiercely loyal to you as a friend, even though you may only be a virtual friend and we actually may never meet IRL.
There you go! A complete social media strategy! It works great for me.