I'm organizing this post with different levels of which you would like to "avatar" your photo.
A Touch of Avatar
f you just want a dash of Avatar goodness to your photo I would go with this tutorial. There's not any healing or liquifying but does show how to change the color of the skin.
A Deeper Level of Avatar
If you want even more of an Avatar look but don't want to work much on the markings the Avatars have this is the tut for you. BONUS: Background tutorial!
For Those That Prefer a More Cartoon Avatar
This one steps it up even more with great skin and marking work. Use this tutorial if you want your Avatar to have a more cartoon appearance. BONUS: Dramatic lighting effects!
Whole Hog Avatar
If you want your Avatar to look like an Avatar as much as possible and the most realistic I would go with this tut. The eye work and the dodging and burning is outstanding.