Okay, that makes things easier in a way, since you already know something about the person who you're talking to.

Imo the best conversation starters are: * Something school / work related * Something you both overheard

Just poke around and try to find something you have in common. It could be anything from a hobby to a political opinion.

If it feels like an interview, that person is not interested/comfortable right now (or at all), and you should probably stop.

Asking for help/advice can be helpful too, especially if it's something small and your target is interested in said topic. And give out small and meaningful compliments, if you're brave enough.

Then again, take my advice with a grain of salt as I'm an introvert myself