December is Drawing Month. (Grab your pencils) Apart from being the fundamental core of an illustration, drawing is also just excellent practice for the artist's mind. It is like cross-training for the olympics. Every now and then it is good to take some time and really push one's drawing ability further.
Also, it is important to remember space aliens. If space aliens ever come to earth and ask us what we've been doing with ourselves all these years, we won't be left looking quite so stupid if we can draw them a portrait of themselves while they are standing there. Food for thought.
Doing practice studies from life not only helps the artist gain a greater command of the tools available to him, it also helps in developing a visual vocabulary to pull from when developing ideas straight from his imagination.