Background:
I drew this in 45minutes during math class which is why it is on graph paper.  I'm not in any classes for drawing, or even an art class.  Sure I doodle every so often but nothing seriously like this.  I did not trace it, I DID draw it.  It is a copy from the album Plastic Beach by the Gorillaz.  It seems i'm only able to draw well, if i see it.  I'm not able to draw off the top of my head, any tips on doing that?

Wow...that's good. And kinda creepy, I love it. Creepy and insanity!

That's hella good man. But really creepy, lolz. Still, it's good overall.

Definitely looks like him.

Interesting, but I'd like too see some realistic work from you. Try to picture the hand you're not drawing with, in whatever pose you wish.
As an amateur artist, I kow exactly what you mean when you say it's hard to draw without any model; I used to be like that myself until recently. Drawing's only dawdling for me, but I've started to be more serious about it and found out that with proper concentration/ application, it's actually quite benefic to your technique to draw ''Off of your head''.
As for the drawing, I couldn't say since I haven't seen the cover, but the pupils positions look awkward to me. The rest, including the shading, is pretty well done.
If you feel like it, I have my own pencil art thread. I'm more of a sketchy artist, but it may prove benefic to your technique to come take a look ^^.

i can draw women posing and stuff ill post one when i draw it because i dont keep my drawings lol and i have to scan it i like the murdoc its really good!

Nice drawing dude.

Strop's right yet again, and you better listen to him; he's a pretty good artist.
Basically, you always have to remember that about 90% of what you'll do will be crappy, or simply not to your liking so you just have to practice, and practice, and practice...

Nice I love it, good shading!!

Very nice sketch. Your should work on those colored pencils though.