I just threw together a quick 3 minute video to go over a few really simple tricks in callrail. In a nutshell just look for short calls/hangups because sometimes those are worth calling back. And remember to use the notes section to document details about each call.
The hangups can result from click to call only, or an ad extension. Sometimes people click on those by accident and then immediately hang up. If you call those people back quickly you can sometimes land a sale.