Wow, you guys are from the land of pretty people.
Pastels are almost as tricky as watercolor...but here goes.
- You have white halos around your shapes. Use some kind of a blending stump or Q-Tip to bring the colors together. But be careful to not whack your drawing in the process.
- Your colors got all muddy. Your ref photo is bright, like really bright, with pinks, yellows, and oranges. Somehow that got moved to grays and dusty browns in your work.
- You lost track of the hard and soft edges of your shadows.
Here is an experiment for you. Get a sheet of high quality tracing paper or vellum. Tape your photo to a window, so there is a LOT of light coming through the photo from the back (or use a light box) and rotate the photo so that it is UPSIDE DOWN. Put the tracing paper over it, then trace all the shadow shapes with a very sharp soft pencil. Forget all the detail of eye lashes and nostrils and just trace the SHAPES of the shadows. Then take the tracing paper to your drawing table and (again, upside down) use your colored pastels to fill in the shadows like a paint by number kit. Then use this as a color study to go back and rethink your drawing.
Drawing shapes upside down will help your right brain isolate the shapes as SHAPES and help you see the colors as colors, and not as an "eye" or a "mouth" or a "baby".
You may even want to turn your ref photo and your drawing upside down too.
Try to pay attention to when the edges of the shadow are hard sharp edges, and when they are soft gradient edges that gently move from one value to another. I have found that the slightly foggy tracing paper has a tendency to make this easier to see. It will also help you see the shapes of the hair as a "form", and that will help you not draw the hair so much like cedar bark.
Pastel is hard, but when you get it right, you can do AMAZING skin and hair with it. Keep practicing and search www.images.google.com
for really good examples of successful ones.
Also, get good quality SOFT pastels. The ones that are hard like the chalk your teacher uses on the blackboard are nearly useless...oh wait, in the new age of dry erase markers, people really dont use blackboards anymore. But anyway find the SOFT pastels, like Rembrandt, or NuPastel.