How do you tell if a flirtatious girl is interested?

I am interested in this girl, she seems to flirt with me a lot and I usually don't see her flirting with other guys. We went bowling with a group of friends and I noticed that she was flirting with another guy, big time. Are there any clear signs that she still is interested in me...and would there be a way I could distuingish myself from the rest of the pact so to say.