Advice to Male Gamers on How Not to Be Sexist Douchebags
In reality, some girls are shitty at some games, but all of them can get better. If you provoke them you're likely to find them sniping you and tea-bagging your corpse because gaming also wouldn't be gaming if rage-filled players didn't find a way to humiliate something that pissed them off.
1. Girl gamers aren't a threat to you: With the above richly deserved retribution aside, you need to be wary of the feeling that girls becoming a dominant force in the gaming industry is somehow a threat to you. This, more than anything, is where men need to step back and consider some things.
Gaming is going to change, and in a big way, and soon at that. Women have precious few good role models in games. Nintendo took their most badass female character and turned her into a simpering, shackled woman holding back her arsenal of abilities to curry favor with a father figure in Metroid: Other M. Mass Effect 2 had a character that you could "cure" of mental problems resulting from an abusive relationship by screwing her. Play through Arkham City as Catwoman and literally all you hear is "bitch" and thugs talking about nailing her. I'm not even going to talk about God of War and Duke Nukem.
At one point, this was a complaint gamemakers could just gloss over because there weren't enough girls playing the games to make their marketshare worth changing. That's already no longer true, and it's going to mean less and less chauvinism will be made or tolerated.
Actually, I guess that is a threat of a kind, but don't worry. There will always be games like the ones I mentioned above. It's just that there will also be games like Portal. It's not feminazism, it's just good business sense. The true essence of manliness is having the character to allow women a place on the server without resorting to a "mine" mentality. If you keep buying games where women are mere ornaments to be won they'll keep making them, but if you scream and throw a fit every time develops makes a title with a strong, female lead then makers will stop listening to you... and probably everyone else.