I found an artist called Sunga Park who has a reires of work called 'Daily Metro Sketches'. These are a series of drawings that Park has done of her fellow metro riders on her way to work each morning.
This is a lot like some of the work I'm currently doing so I can easily draw influence from her, especially when it comes to drawing from life. For instance she focuses only on the parts of the person that seem necessary to capture whatever it is she is trying to capture about them like their posture or what they're doing. This leaves gaps in the figure but you can still tell what's going on. Her work has also made me realise that my work from life could benefit from going bigger as to make things clearer like her work. I also like how she goes back to the drawings later to add colour, this makes the sketches seem more like complete illustrations.

Source:  http://www.behance.net/gallery/daily-metro-sketches-female-1/11168855