1. Read media by people in the group. Fiction, nonfiction, blog posts – anything from “how my day went today” to 300-page epic adventure novels to history pamphlets. (By people in the group, not just about them. This is important.)
2. Google “How not to write a [the group] character” because the odds are that at least a few people in the group have written blog entries rattling off all their least favorite tropes representing their demographic. I’ve seen lesbians writing about how not to write lesbians, Asians talking about offensively-written Asians, etc. Refraining from writing the overused, negative, one-dimensional tropes listed in posts like this is probably a good start.