Easy: make diverse and compelling characters. Create a diverse cast. It's not even about feminism or anti-racism/oppression. It's just good, realistic writing.

And I hate excuses like "but the [i]time period[/i]" because I'll throw [i]A Song of Ice and Fire[/i] in your face, which has a good mix of men, women, white people, colored people, queer relationships, and disabled people but takes place in a medieval fantasy setting. It acknowledges issues that are still problems today, but through characters. It adds immersion to the story. No one is "colorblind" and there's plenty of sexism, homophobia, etc...But there are also characters who are basically embodiments of "fuck you" to those attitudes--WITHOUT making the story all about those issues. It's perfection, imo.

Stories comprised solely of straight / white characters are not only boring, but make no fucking sense. If you just include good representation in a role play or story, you basically solve the problem.