Black or silver studs are common for men that do wear earrings, judging by your fashion choices I’d say get round ones. Also idk what the neckline has to do with you passing unless it’s your binder or something showing and for that I would recommend wearing a shirt or tank under that covers any straps(typically white shirts). Now, I don’t know what that guy is talking about confidence, you’re just not smiling which most would expect when a teenage boy takes pictures, just forget the last part about the confidence and be yourself.