Did these today on the train to and from work. I figured out that if I just take a quick glance of someone and try and draw mostly from memory I don't get bogged down in details. I do obviously look up during the drawing but I try and limit this at the beginning.
I spotted this lady early on, she wasn't quite as old as she appears here.
Then this woman sat opposite me, so I quickly captured what I could without arousing suspicion. Em always tells me I make to much of a head motion when I'm observing so I'm trying to remember to only move my eyes.
These were done on the way home whilst watching the remake of 'Of Mice and Men', which was predictable to say the least.