Great tips there slynky.

To highlight lips I do something like this (though it may not be the best way, I don't know...I like to take short cuts. This may be dangerous;)

-->Select and Feather the areas of the lips you want to define

-->Create a New Layer while the areas are still selected and Fill with a lighter color, Opacity at something like 25%. Then contract the selection and Fill again, Contract and Fill, Contract and Fill....untill you have achieved the desired definition.