What is the protocol for messaging Facebook friends who aren't your real friends?

[The Ninth Answer]

There's a girl I'm Facebook friends with who's real cute, but the only way I know her is because her sister and I had high school classes together. I'd love to talk to her in real life, but since that's not an option at this point, is it socially acceptable to just start opening a Facebook conversation with her?

[vishnuprasadu]

i think facebook is fine to start a conversation... i can give one of the example that sometimes i found some of my friends of friends living in a place that i wish to go and after i will ask them suggestions about the places and we become friends.. so i think its fine it will work. your medium may be facebook but your idea and words are from you and its real. so its fine but dont keep talking only in facebook good luck!