Gained by completing an imaging session.
You can gain one-third the XP by working on yourself.
You DO NOT have to actually change a feature to gain the XP, just complete the session.
Hairstyle 4: Eyebrow Shape [eyebrows] (125xp) --> Facial Customizations 2
Facial Customizations 2: Nose Width [nose_width] (150xp) --> Facial Customizations 4
Facial Customizations 4: Jaw [jaw] (275xp) --> Master