I met this girl yesterday...?

So I was at work yesterday. A coworker of mine came to pick up his check and he had two friends with him, one guy, and one girl. He came behind the desk (I work at a hotel) to get the check so I pulled him off to the side and asked him who that girl was. He said "That's my friend Lacey. You think she's cute or something?" and I said "Shoot yeah!" So he brought her over and he said "Wes wanted to meet you cause he thinks your hot." and I looked at her and said "Actually I said 'pretty'." and then she said "Aww...thank you." and I said "Youre welcome". So then me, her, and my coworker just sort of stood there and talked for like 3 minutes maybe and then they left. I dont know what Lacey thought of me though. How can you tell if a girl might halfway be interested in you after the first impression? And after my coworker introduced us I didnt have any clue what to say to her. What would you say to a pretty girl that you've just been introduced to?