How do you stop pastels smudging on a pullip?

Buy Paint and Pastel Fixitif spray from an art store :) I customized one of my pullips and sprayed a few coats on, and it worked just fine :D

Also please READ THE DIRECTIONS before spraying it because you must shake it first, and apply in 9 inches away from her face, using a back and forth motion. Three coats is advised.