By default, this is the only privacy strategy which makes sense anywhere on the internet, for the average user of large scale services.
Whenever you post anything, anywhere, but particularly on any kind of public forum or social network, assume it'll be seen by your current and future coworkers and grandmother. Assume it'll be the post/photo/video used to identify you on the news if you're ever in the news for anything.
If it's still ok, post away. If it's not, consider why you're sharing it on a social network anyway, and if it's still important to share with a select group of people, then consider sharing it by some other means.