you see a girl who is newly single on fb and posts it for everone to see and talking shit about her ex. what is a good way to open them, especailly if you don't know them well or at all?

I've done this recently. Go down the route of being sympathetic - say you hope she is ok and you are only sending her the message because you went through a similar thing recently (i.e. its not just a message out of the blue - you are being understanding)

If she replies you've gotta make the next message funny or with some kind of hook to it. Try to get a conversations started. Once you've exchanged a few messages step it up with a flirt or two and then you can be like "hey, nice chat! If you fancy going for a drink sometime I'm game" or something.

I wouldn't go down the route of slating her ex too much though. Just be sympathetic and steer the conversation away.