If the repeater is inactive and you want to start a conversation with any station, simply state your callsign followed by "listening" or "monitoring". If station is listening and wants to converse, they will respond with their callsign.

Do not call CQ on a repeater to start a conversation. There is no need to repeat the "listening" message over and over as one might do when calling CQ on HF – once every few minutes is sufficient. Avoid using bad sci-fi movie lines like "is anybody out there?". Be sure to actually say "listening" or "monitoring" after your callsign, as stating your callsign alone is confusing, if not meaningless, as stations who may be listening will not know if you are monitoring for calls, or if you were making a test transmission, or if perhaps they missed the callsign of the party you were calling.

Stating that you are "listening" or "monitoring" does not mean that you are listening to somebody else's conversation already in progress, and neither term should ever be interjected into an ongoing conversation. There is no reason to announce that you are listening to other stations' communications.