Status updates are an easy way to start a conversation... it's a public thing, it's not like you'd be looking on her profile for it.. I mean, you can, but they show up on the main facebook stage, lol.
You can give a shot to talking about the good friend you guys share.
You poke them! Then just have some witty/funny remark to follow it up with. I usually go along the lines of saying "Didnt your parents ever tell you its not safe to poke strangers? :P " (I took that from someone roughly, the whole technique, forget who, sorry)
I wouldn't completely randomly start a chat or messaging, I don't find it to be too successful.. Might work if you have a good topic though. I've been getting a lot of girls to talk just about our college plans if they're heading to the same one as me.
“Self-pity is easily the most destructive of the nonpharmaceutical narcotics; it is addictive, gives momentary pleasure and separates the victim from reality.”
Don't lecture DHV,