Start inserting on a new layer the make-up of the eyes, using the Brush Tool.

the little mermaid

Change the layer's Blending Mode on Overlay:

the little mermaid

Get back to the basic layer and make the flares on the girl's lips brighter, choosing for this operation the Dodge Tool.

the little mermaid
  


Create one more layer above all of them and continue by representing on it the make-up of the eyes, choosing a different color:

the little mermaid

Blur a little the layer, applying Filter ? Blur ? Gaussian Blur.

the little mermaid

Change also the layer's Blending Mode on Overlay:

the little mermaid