Return to the skin's layer and select a darker color for representing the shadows. First picture the shadows around the eyes with the usual Brush Tool and blur them out with the Smudge Tool.

drawing Melissa elf - girl in adobe Photoshop cs2 


drawing Melissa elf - girl in adobe Photoshop cs2

Insert after that two more shadows' nuances (lighter one and darker one than the previous shadows). Use the same two instruments applied earlier.

drawing Melissa elf - girl in adobe Photoshop cs2 


drawing Melissa elf - girl in adobe Photoshop cs2

Using the same method, it's possible to give volume to the girl's body.

drawing Melissa elf - girl in adobe Photoshop cs2

The layer's Opacity
 
must be 100% again. Choose the Brush Tool (with the same adjustments applied in the eyes' processing) and represent the skin smoother than it is with accurate, blurring motions which must repeat the shape of the pictured volume.

drawing Melissa elf - girl in adobe Photoshop cs2

The image that we've got looks dimly, that is why we must correct the brightness and the contrast, making use of the next command: Image – Adjustments – Curves (ctrl+m).

drawing Melissa elf - girl in adobe Photoshop cs2

Make use of the Brush Tool (100% adjustments) and the Smudge Tool to represent the girl's lips on the skin's layer.

drawing Melissa elf - girl in adobe Photoshop cs2

Select the Brush Tool to correct the skin around the lips.

drawing Melissa elf - girl in adobe Photoshop cs2