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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Sure, I'll be courteous to whatever trans person I come across, provided they make it very clear what they are; but forgive me if I call someone who looks, talks and acts like a girl, well, a girl; and then they get offended at me over it.[spoiler]But the second somebody says they identify as a wombat: I'm out[/spoiler]