Most Helpful Girl
Be genuine, kinda cute and smile. If you are at one of those mixeology bars tell her you haven't been there and ask what's good. On the street if she isn't distracted (works in a downtown setting) ask her the time at a crosswalk or something then say 'thanks I really just wanted an excuse to introduce myself I'm (inset name)" In a casual way. If she smiles and gives you her name say it back tell her which building you work in and maybe you can get a drink after work sometime?
She might have a boyfriend or just be too shy to go with it but either way 9% of the time you made her day better and it will be easier the next time you try it. :)