If or better yet when, you meet a trans person, regardless of how you personally feel about them, at least show them the same respect you would show for anyone else. That means addressing them by their preferred pro-nouns (he, she, they, them, it) and name (self-explanatory).
It's easy, and it'll make you look like a much better person.
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If someone is biologically a male, but tell me they identify as a female, I will disagree with them (respectfully), and that's just something they will have to deal with.