small talk, find things that you have in common but don't act like a complete nerd by bothering the girl too much.
after a while it will stop being different than talking to your friends for example. Having female friends also helps. Going out with friends might also be a good opportunity to meet girls/practice talking to girls.
Bonafidenever be yourself btw, horrible tip, be yourself when you're sure she's not going to leave your nerd ass.
Totally have to disagree with bona there, surely you can be yourself without having to talk about videogames 24/7. If you can't find anything in common and you'd have to be someone else in order for it to work, you might as well stop dating her. Cus if she ends up falling in love with you because of that, then she falls in love with who you're pretending to be.