Agreed. I went through a program using that book this year. Great stuff.
As I remember it, your left brain-half manages imagination and therefore tries to tell you what it thinks the thing you're drawing looks like. The result is usually a standard way of drawing something you've learned youself. You Right brain-half covers math, and will process things exactly as you see them. It's better at copying things, so when you draw models or objects and don't use your imagination to fill out the blank spaces, you get results you wouldn't get the usuall way and gives you something you can learn and use later on.
As for what you're doing now. I would reccomend you get the shape right first. There's very little good colouring will do if your motive looks odd and disfigured.
Little edit:
Hope it helps in some way. 
Thirded. I saw that book at a library, read thru it. Very helpful and true. Draw what you see indeed.
Dithering, in my opinion, should be used sparingly. The way you have used dithering to shade the eye and nose area should probably be scrapped, as it 'dirties' the area. Realistic hair is very hard to achieve at small resolutions (haha, realistic hands are even HARDER), and thus, it might be worthwhile to consider flat shading, especially at low resolutions.
Yeah, you're one of the more mature people who come here, it seems.
Oh yeah, and on the topic of random drawing, I find it's really good, once you have a grasp of form, shadow, light, etc., to just doodle, straight from your head. I know I do it in classes where I don't learn anything.
Just random things that come to your mind, doesn't even have to exist in real life. Let your imagination loose, see if you can sketch the image in your mind, you know.
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