How to ask her out for coffee without looking like a weirdo?

I have been talking with a girl in my university for some time. But we mostly talked about studies only (she is a nerd). She is single as much I know and I like her a lot. I want to ask her out for coffee but afraid. If she is not into me and reject I won't be able to talk with her again😢.

How can I ask her out without making things worse?