Talking to Otaku girls

If you are in the same class it should be a lot easier to talk to someone. Why not try "Hey hows it going?" Put less emphasis on her being an otaku girl and just talk like you want to get to know her.

Just approach and talk to them like you would with any other girl. Girls who are into geek stuff like anime, games, etc are great sure, but they are just like any other normal human girl you'll meet. Just say hi and talk to them naturally, it's not hard at all. If she thinks your cool then she'll have no problem talking about anime and all that good stuff.

Does she wear her fandom on her sleeve? I'd say maybe see if she's wearing any sort of anime stuff or if she has stickers or pins or something anime related on her backpack and maybe approach and make a compliment about it as an icebreaker and go from there. Ask her what kind of anime she likes, what she's been watching recently, etc. Just be relaxed, laid back, and casual and take a genuine interest in what she's saying. If she doesn't have a lot of otaku friends in school with her, she might appreciate someone she could talk to about certain shows before class and during breaks.

^ basically what they're saying, just find out what exactly she's into and just out of nowhere mention something related to the anime and she'll feel instantly good talking to you. It's much better than starting off casual. That's how I make my friends haha.