Share Your Process Of Creating Characters Across Cultures Or Class

Crossing boundaries of culture, race, and class to create characters can be tricky, but as fantasy/romance author Mary Anne Mohanraj thoughtfully points out, "You will get it wrong. This is what you should do."

Children's book author A.C.E. Bauer makes the case that we can't include a character of a different race without seeing that "it's not like choosing the color of her hair."

It always helps to learn from one another's mistakes and processes, so I'm seeking input from my fellow writers. Here are my questions, and they apply to historical, contemporary, dystopian, and fantasy novels:
  1. When you crossed boundaries of power (cultural, racial, economic) to create characters, what behind-the-scenes homework did you do (research, interviews, etc.)?
  2. Did your editor ask for more research or tweaks when it came to issues of race, culture, or class? If so, when and why?
There are no right or wrong answers — basically, I'm looking for tips that we might all find useful. I'd love to compile comments, so share titles, release dates, and publishers of published works, and working titles of books-in-progress. Thanks!