New is scary but....

Camera makers have invested millions designing your camera so they must know whats best? So why have they given aperture, shutter and manual modes? Simple, there will be times when auto mode will not select the correct settings.
I mainly shoot in aperture mode and it really is simple to decide F2.8= Faster shutter speed + smaller area in focus, F16=Longer shutter speed + large area in focus. So sports/wildlife open the aperture up (smallest "F" number), Landscapes F11-F16, Portraits F5.6-F8.  These settings are not final, but a starting point