When my wife and I were hunting for an FC to join, we took note of some of the more frequent FC tags we would see. Over the course of a week, we would send a tell to a random member we saw and ask what they thought of the FC they were in. We were specifically looking for an FC with frequent events, so we would ask about that.

Remember to View Company Profile on players in game to see the size of an FC and its current number of online payers.

One final note is there's nothing wrong with joining an FC and then leaving. Just drop a friendly note saying you're looking for something different and go.