The first workshop I participated in was given by Lynne Chapman.  I met her last year in Santo Domingo and correlated her expressive sketching style with her buoyant personality.   True to form, the workshop was lots of fun.  My take-away was cropping and using angles to create interest.  She suggested zooming in on an object and filling the page. Of course, true to form, I started with the interesting root buttress of a Plane tree, before moving to buildings.