Just be nice to her. Say hi when you see her, if you have a second, ask how her weekend went or if she had plans for the upcoming one. Simply compliment her, casually say something like "oh, i really like your shirt" or "you look really nice today". Just little almost offhand comments. If that helps you get talking more, then start saying things like "hey lets chill sometime" or "want to grab a coffee and talk about a class you've in common".