My friend Bob Staake posted a video that shows how he illustrated the cover of the latest New Yorker. He still uses Photoshop 3.0 and Macintosh OS 7!
I suppose I have a pretty unusual way of working — at least that's what my illustrator friends are always telling me. I start by creating the most basic shapes and then refine with details as I go. To me the process feels completely normal. I look at that stark white space in front of me and can see the entire fully completed image in my head. Maybe I'm just lucky that way.