Who can see what?
On your own profile stream you can see all your posts but those not in your circles can only see your public posts. If you share a post with only one circle, you as the originator, can see it again on your profile ‘Posts’ page, but no one outside that circle can see it.
It has been discussed among the Google+ community that leaving someone out of a post in a circle would be nice, we shall see if this is a coming feature. -Mr X instead of +Mr X? At the moment you can just temporarily remove a person or persons from the circle you’re posting to and perhaps create a ‘Temporary’ or ‘Holding’ circle where you place the person for a little while.
Is there something else you'd like to add?
Re-share: Public or limited?
People have been asking me about the etiquette of re-sharing, here are my thoughts:
Some folks share only to their Circles so personally I would check with them is it okay to re-share publicly or if you post the link as your own, would they like to be mentioned in that post. There might be some reason why it was not shared in public. To be on the safe side, share max to ‘Extended Circles’.
I would recommend, if sharing delicate matter, the original poster should mention ‘Not for Public’ or ‘This Circle’s Eyes Only’, then the sharing dilemma would not exist. And disabling re-shares (Lock this post) from the options menu at the bottom right helps, too, before hitting 'Share'.
Clicking the ‘share’ under the original post means that the original poster sees the share. Unless it has already been re-shared and you are actually sharing that post. The comments in any shared post will not follow, nor does the originator see your comments.
Please be polite:
No matter with whom you share a post you’ve found in Google+, it is always polite to mention the person who shared the post before you. Simply add ‘Via +Mr x’ or ‘Thanks for the share +Ms Y’. Also it is very nice if you write your opinion about the post you are re-sharing. (Or just a few words why you share.)
Disable comments on your re-share?
Linking the original post to a new one by clicking on the ‘time stamp’ and then posting the permalink is a good way to credit the original sharer and keep your own commentary intact for possible reshares. The downside is the original writer doesn’t know that the post has been shared, unless you mention them in your new post text. If the comments are really good in the original poster’s thread, sharing the link and then asking people to comment on the original while disabling comments on the re-share is a good practice.
You can also open the drop-down menu from the grey arrow on the right hand corner of a post and click 'link to this post', then you'll see the URL for that post.