I've always liked Nicolaides' technique of contour drawing in The Natural Way to Draw. Trains the eye, & the hand to work with the eye. The pure method asks that you don't take your eyes off the subject. (Definitely unsettling but good learning.)
I just got brave & tried a new version of contour drawing: Not (almost not, in my case) lifting the pen. You start in one spot & just keep drawing with a continuous (almost continuous, in my case) line. It's interesting to focus on one small part at a time of the whole view, & it does get you out of preconceived notions of what the things are & into observing their abstract lines & forms. It's a surprise to see that at the end, a whole composition has filled the page. It almost feels like it did it on its own.
(This scene is a view to the kitchen counter, drawn while I was listening to a TV show.)