Never, ever post a comment on your kid’s Facebook page. Not even a “like”. Don’t post anything on their friend’s pages either, if you are lucky enough to have any of them “friend” you. Pretend you know absolutely nothing about Facebook and have completely forgotten that they are even anywhere on there.
There will be times when this will be incredibly difficult. Comments will swirl around in your brain, trying to bash their way out. “What were you doing online so late last night? Your friend posted a picture of you that wasn’t very flattering. Why are you sad? What’s wrong, honey? Who is that person who kept commenting on your wall?” Believe me, if they post it online, they aren’t talking to you. Advice from mom or dad is completely unwelcome, especially if things are not so rosy. Even words of encouragement just look lame if they come from you. “You just follow your dream!” or “Don’t listen to so-and-so, they have no idea what they are talking about, you are wonderful” work negatively when posted where all can see.
If I ever did look at my daughters’ profiles or posts (which, of course, I don’t), or, heaven forbid, see something on my own news feed that they have posted, I would only use it like I do any other cue from them. Maybe I’d ask about their day and give them a chance to air out any problems directly or indirectly. I’d make sure they had a chance to hear how wonderful they are directly from me. Face to face, not Facebook to Facebook.
Resist the urge to comment. It’s akin to a rabbit freezing when in the gaze of a snake. If they don’t see you, you aren’t there.