How to start a conversation with someone you don't know?
Start with a greeting and an easy-to-answer question. A message related to the room or profile shows that you're addressing that person, rather than sending the same formula to the entire community.
Some starting points
You can ask 'What are you listening to?' after seeing an interest in music, or 'You were talking about hiking: any places you'd recommend?' in the room. An open-ended question invites someone to share something, without requiring personal information.
Respect the first exchange
Introduce yourself using your nickname and keep a simple tone. Avoid immediately asking for a number, address, photo, or webcam. If the response is short, adjust your pace; if it doesn't come, leave the person alone. Everyone can read, be busy, or not want to continue.