It was a long time ago, so I thought I make another quick tutorial...
I usually don`t really like to use references - I am making loads of sketches first to establish my characters and kind of compositing the best parts of my drawing to get the final base sketch for my concept. Though I think using some reference image to get your character right is absolutely necessary, if you want to achieve a more realistic image in a short period of time.
I made this image really quick (a bit more than an hour) as I wanted to focus just on my working method, so please forgive me the anatomy faults on the final result (shit - her face turned out totally flat at the end!).
I hope it can help you somehow and feel free to ask, if you have any questions.
final image >>>