I'm currently taking an excellent online Craftsy class with Montreal artist Shari Blaukopf entitled "Sketching the City in Pen, Ink & Watercolor." I can't recommend it too highly for those interested in urban sketching. And, no, I am not connected with Shari or Craftsy other than as a student. She breaks down various aspects of sketching in the city and hones in on what to include, or not, which I am finding invaluable for my virtual paintings via Google streetview. I'm hoping to brave the weather and get out for real life sketching in the near future and I think what I'm learning in this class will be my ticket. When I lived in Hawaii, I painted on location at least once a week but I was more interested in landscapes, seascapes, and florals than urban sketching. I wish I had had access to Shari's classes way back when!