Are there any tell-tale signs that a girl is interested in you? Or is this just one of those things where I have to take the chance and see if my gut was right in telling me that she's interested?

How do you guys go about this? As an example, there's this girl I'm really interested in at one of the stores that I frequent. She invited me out to a Halloween party but it was less of a "you and me" kind of invitation and more of a "stop on by" kind of invitation.

Thanks Reddit and happy Halloween!