Sketches using : http://artists.pixelovely.com/practice-tools/figure-drawing/
If I am able to I will often fit sketching in while on the train or sitting in areas where people are visible. I often use a simple ball point pen to sketch when travelling for ease and permanence.
Charcoal Drawing from visual research classes using cardboard cut-touts to better frame the image. I really enjoyed using these as I found I was able to better keep my drawing in proportion while also knowing how much space I would fill with the drawing.