I just noticed that one of the unkillable questions for fiction-writing essays is being asked and answered twice at Tor.com: Kate Elliott is doing Writing Women Characters as Human Beings and Ilana C. Myer is doing Oh No, She Didn’t: The Strong Female Character, Deconstructed. Now, I haven't read either, so this post isn't to disagree with any of their specific points.
It's to disagree with the approach to the challenge of writing women well.
Because identitarians insist people of different social identities can't write "the other" well, I'll note that the feministsf wiki said my “work features strong women characters and people of color”, so if you think I'm not entirely disqualified to speak on this subject, here's my advice:
Don't write men.
Don't write women.
Write people who love some things and hate some things and want some things and don't want some things. Write people who agree with some aspects of their society and disagree with others. Write people whose assumptions about the world are constantly being challenged.
Make those people specific. Unless you're doing a fairytale in which the point is that you're writing an Everyperson, define the character as thoroughly as you can while remembering that no single characteristic is the whole of a character. Huckleberry Finn and Becky Thatcher's defining traits are not that one's male and one's female.
Advice about how to write men and women is always wrong because it begins with the assumption that writing one sex is different than writing the other. If you can't write people, you'll never be any better at writing men or women than you will be at writing tall and short people, or loquacious and taciturn people, or trusting and suspicious people, or obedient and rebellious people, or cruel and loving people.
Here's all an artist needs to know about writing believable characters: people are people. If you don't understand that, all the information you're given about writing an "other" of any race or sex will only be information about how to write a stereotype.