RE: What do you do when you Don’t see the airplane in the air?
I used to fly at a nearly abandoned airport with the owners permission. I was flying a mostly white airplane when I heard a full-scale approach. The Cessna was not landing, but I couldn't find my plane after looking away in the hazy blue sky. After about ten seconds, and afraid it would fly out of sight, I began doing continuous loops. The sound focused in one part of the sky helped me locate it in another few seconds.
I learned two lessons that day. Never fly alone if you can help it, and put on some contrasting stripes. I've never lost sight of a plane since.