Occassionally a good looking woman will add me on facebook. I accept the request, but don't know what to say to start a convo. They don't start a convo either so nothing happens.

Most of the time they know who I am as they went to the same school but were a little younger. Some have mutual friends on facebook but I don't know who they are.

I know it's possible that they might be a person that adds everyone who they are aware exists, but with some of them I feel like I've missed an opportunity

How should I approach this? What woukd you do in this situation? Thanks