[Spivak pronouns: ey/em/eir/eirs. Spivak pronouns do not connote a gender. Usage compares to they/them/their/theirs, sie/hir/hir/hirs, ze/zir/zir/zirs, she/her/her/hers, etc.]
You cannot accurately assess a person’s gender identity or their pronouns by looking at them nor hearing them. You can only know someone’s pronouns and identity by asking them.
The assumption that you can just guess - that there’s no harm done by looking at someone, deciding what you think their gender is, and feeling entitled to just project your assumptions onto them - is busted. It erases the pain that misgendering can bring; it reinforces the busted societal assumption that your perception of someone’s gender is more legitimate than their actual identity; it reinforces the cissexist and extremely binarist assumption that gender non-normative people are rare and don’t really matter or shouldn’t merit consideration. It also means you WILL make mistakes and misgender people; given that our assumptions about people’s genders are shaped by a binarist, cissexist, and sexist society, this means that your mistakes will generally be w/r/t non-binary and trans* folks.
So, since coming to realize all of the above, I’ve come to a simple solution: I ask everyone their pronouns. Yes, everyone, not just ‘people who appear gender variant:’ that very categorization hits the same busted issues I mentioned above, AND relegates ‘people I perceive as gender non-normative’ to a status of ‘marked other’ while ‘people I perceive as gender normative’ is left as an unmarked default.
I’ve only started this quite recently and have done so somewhat inconsistently while I fight to actually remember to do this and not to default to my socialized impulse to just guess anyway. It is not actually difficult! Most of the time I don’t even need to ask, as it simply doesn’t / won’t come up; many times it comes up and I can follow their lead or that of people close to them without needing to directly ask; and when I do ask, it’s quick, easy, and relatively painless. I have gotten some backlash from reactionary people on this who proceeded to mock it, so I can’t advise it for everyone all the time. My own binary privilege is pretty salient here.
That said - obviously, if I have no means of contacting a given person, I can’t ask them. So, when I reblog an image of a person devoid of other info about the person pictured, if I have literally nothing other than the pictured person’s appearance to cue me, I can’t guess. So, I’ll use gender-neutral pronouns - usually ey/em/eir/eirs or ze/zem/zir/zirs. Though I’ll probably switch it up.
This applies to non-human animals too. For example, saying your cat is a ‘boy’ because you know it has a penis is busted on general principle; you think it’s fine to equate gender and genitalia. This is despite the obvious cissexism and the simple fact that you have no idea if your cat experiences gender of if such an experience is anything like our perception of gender.
And clearly, fictional characters are a bit fuzzier in this regard, as authorial intent can usually directly convey what that character thinks. So, I’ll usually act like I *can* read that character’s mind. Like Gaara. Mmmmmm.