1) Be explicit that you’re caring about women participation, even if it may seem obvious to you. Include in the event description that women are welcome, partner for the communication with a group that is associated with a female context, like Girls in Tech, Rails Girls, Women TechMaker or any other reality of the local ecosystem, use creativity that includes both genders. Fight the language stereotypes: in Italian we use the masculine for referring to the whole category, so use explicitly “sviluppatori / sviluppatrici”, instead than just “sviluppatori”. Remember, you have to communicate that you’re caring about the whole spectrum of your community, all the minorities included.
I have to say that both tips don’t come out totally of the blue: there are different studies on gender inequality in schools and in business, and we all see the world behind the lens of unconscious bias, so the same situations applies also in a community. In addition, once discussed deeper with the attendees, asking the whys and the whats, everything resonates very well together. Happy to provide more details in the comments, if asked.
As final suggestion, if you decide to apply these two simple tips (and you should), please make an additional third step: ask for feedback to the new women at your next event, ask if they come thanks to one of the suggestions you’ve put in practice. I know it can be hard but, as for any hypothesis, it has to be verified.
Those learnings, I think, can be generalised to each event than want to include a minority. Maybe women, maybe any other. Explicitly be inclusive, do not take it for granted. And yes, I’m still generally agains gender-only events, but it had a sense in this particular context.