Firstly game is game, whether in an office, on the street or even in a bar!

Just start talking, if she floats your boat make you intentions known that you want to grab a drink/dinner/sex!

Although there are 9 men for every woman, i find situations like this are the best because all you need to do is show you are a decent guy who is different to the rest of your hoard and you're in (as most other guys just walk over trying to impress with houses, cars, muscles etc.)