Methods I myself find useful for improving my depictions of minority exeriences, other than “sensitivity readers”
Try to privilege nonfiction sources on your topic (like “Being poor at an Ivy League college” or “Clothes of Japan” or “Women’s Experiences in the Armed Forces, 1939-45″ or whatever) written by the people they’re about.
Seek out memoirs, diaries, and other personal accounts of people who lived the experience you want to know about. The previous category of book will tell you that a regulation was X; personal accounts will include things like, “Then afterwards we all went out, completely ignoring Regulation X, and did Y thing all the livelong day.”
Find cultural informants, people willing to talk to you about their experiences, and listen to them raptly. Get a sense of who they think they are and what they feel their experiences meant. Do them as much good as you are capable of, because their stories were a gift to you. If at all possible, be up front: “I’m a writer, considering writing about [topic]. I’m interested to hear your experiences.” If at all possible, ask: “Would you be all right if I included some of what you tell me in my work?”
Find members of the minority group who have written criticism of their fictional depictions, especially recent ones, and read it.
At the same time, look back to criticism from older generations. Thought shifts as trends shift and social change advances. That way you’re acquiring not just a checklist of what to do or not do, but a sense of how society has changed and how problematic tropes used to be considered. As a creator, you have the ability to manipulate tropes and change perceptions; you might as well know how that’s been done in the past and where it’s going in the future.
As you go, consider the diversity of experience you’re dealing with here–two people with the same backgrounds and living through the same events may have wholly different experiences. This is important, since you are not writing the impartial embodiment of an experience, you’re writing a human being. At some point you’re going to have to decide which particular quirks or opinions your own character takes in; acquaint yourself with the spectrum of possibilities.
Find a depiction similar to what you intend to write, and go search out its fanbase. Watch their fanworks, blogs, and discussions with alertness to how fans respond to the issue you care about–what they knew or assumed coming in; how they interpreted the media they consumed; how they’ve responded since them. This will give you a reasonable model for your own audience.