Ana goes back for gems of advice for introducing characters in "Self-Editing for Fiction Writers"
"Once you understand a character well enough to bring him or her to life, we don't have to know where the character came from."
"When you defined your characters the minute you introduce them. you may be setting boundary lines that your readers will use to interpret your characters' actions through the rest of the book. But if you allow your readers to get to know your characters gradually, each reader will interpret them in his or her own way, thus getting a deeper sense of who your characters are than you could ever convey in a summary.
"Sketching out your characters for your readers is just plain intrusive. It's a form of telling that is almost certain to make your readers aware that you the writer are hard at work."
"It's often a good idea to introduce a new character with enough physical description for your readers to picture him or her. As with describing your settings, all you need are a few concrete, idiomatic details to jump-start your readers' imaginations."