It looks like you're doing the scetching by hand and the final line art and colouring in the comp, am I right? And fuck, I'm so jelous of those lines >_> You have seen my stuff, right? A totall mess.

I don't have any tip for you concerning the mustache, I've never really drawn that either ^^ but I guess you shouldn't bother about the lips - do the mustache before you do the mouth?