What does a dragon need to stay safe? If you read The Hobbit, Smaug the dragon was killed by an arrow that pierced a soft area in his skin under his arm. Dragons have to have a strong skin..
So what would it look like? I’ve been experimenting with how big the scales would be. I guess they would have to be like an alligator or crocodile skin, rather than a lizard or snake whose scales seem smaller or softer. The dragon would need fire retardant scales to prevent charring or burning either around its mouth when it is fire breathing or on the rest of its body. Maybe male dragons duel in short fights, if they were to attack each others wings they would need to be strong. Dragons wings always look vulnerable. The skin is stretched between bony fingers. Surely that could easily be holed if it were not well maintained. Lots to consider.