How do you start a conversation with a guy you don't know over facebook?

To start a conversation with a guy you don't know on Facebook, begin with a friendly and casual greeting. Introduce yourself briefly and mention any common interests or mutual friends that might serve as a conversation starter. Keep your message light and open-ended to encourage a response. For example, you might say, "Hi! I noticed we both follow [common interest] and thought it would be great to connect!"