I have heard from multiple people that eye contact is essential in letting a girl (or guy, I guess) know you’re interested.
But what is the 411 when it comes to said eye contact? Do you keep looking until she does? Do you then keep staring? Or is like looking at the sun? What’s the deal?
So I think the question could be refined a little. Eye contact helps build connection between people, but it’s not the only piece of the puzzle. Maybe a better question is “'How do I communicate more empathetically?”
There’s another question; “How do I let someone know I’m interested?” This question is related to the first in that trying to get close to another person (being vulnerable with each other) and communicating your feelings is how you let someone know your interested.
TLDR: get to know them and tell them you’re interested. If they say they’re not interested you can probably still be friends since you already got to know each other. Empathy and humility/vulnerability are key in building relationships.