Don't laugh, but um... I sorta nearly... teared up... when I scanned this in and took a look at it. Shel Silverstein holds that much nostalgia and moments of clarity and poignance from my wee youth. His writings quite possibly could've been some of the first that I read that made me 'get it', that underlying moral, or emotional underlying story.
Of course, I'm talking about his articles from Playboy.
The trick to his style (I dunno if he employed this or not, but it worked for me in imitating him, at least), is that my first pencil lines laid down were pretty much the final placement of structure- as in, I didn't sketch any super light form of ovals or gesture drawing underneath. Rather, I went contour to contour. . . Maybe a hair too much stippling for Shel's look, but I think I almost NAILED that face. Hope you enjoy.