This is something weird I noticed with my own writing style. I'm so used to opening with a paragraph where I simply name the character and give a brief description of where he is and what he is doing. Most of the people who read my type of story should be familiar with who the character is, their background, how they look, move, and sound. When I started a story where the main characters' first mention is the first time they drew breath, I was actually wincing at how far I was getting into what they were doing without calling up any detail about what they looked like, and only the barest nod to their surroundings. Really broad question warrants example, so how do you deal with a character's first breaths vs their first appearance in a sequel?