There are many situations in uni life where you can approach a girl with any situational opener.
An example is this one I have tested it few times,
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While in line in canteen, comment on her choice of food and based on that predict her personality (be funny and use a neg). Ask her to eat together.
If you see a girl from your uni/campus somewhere else, simply tell her that's she looks familiar. Ask her if she's following you (ofc with a smile).
Uni and campus is the best for situational openers, go with the flow. And if you can't think of any situational opener, classic ones (hey I wanted to meet you) and clichés will also do. E.g. at uni ask her to borrow a pen. Tell her that you don't need a pen, you only wanted to meet her. While saying that you can draw *anything* on piece of paper with her pen, and hand it to her.