As a cis gay man, it's important to admit that I've had huge blind spots about women in our fandom and I'm still learning about the ways my gender privilege prevents me from seeing all kinds of issues women have to face. I'm eagerly learning how to be a better ally.
But at the very least, shutting down people being shitty about women in our circles is one thing we can do. Sexist remarks, even 'playful' comments about feminine characteristics being 'gross', lame 'jokes' about women's bodies need to stop, period.