A Perfectly Respectable Alien

Pretty good distort and apply texture. Try using Displacement Maps as well. They help with distributing the textures. You can see tuts about that everywhere. Some good ones are at psdtuts.com. I see you overly distorted the lips so that you could see the pixels tearing. You need to feel confident enough the paint the detail back in or overlay a copy of the original using the sexiest of modes: luminosity. Or even simply use Multiply. You can just get the lipline with that. It is easier with white people though because of the contrast the lip line against the pale skin. I cannot tell the subject's ethnicity here, but with darker skin (which makes great displacement maps) you will need to up the contrast to get the lip line only. Once it looks pencilly with only the basics you would just manipulate that with distort or warp (if you have it) and multiply it on. Good Work and Good Luck.