Does anybody know if there is a tutorial to make a fondant princess or have any helpful hints? I need to try and figure out how to make the diamond castle barbie princesses.

How big do you need to make them?
I made a princesscake with an edible Barbie, instead of a doll. I made Flowerpaste (RI mixed with Tylose/cmc) and then used one of my daughter's Barbies to make a mold of the face.
I made the princess then of Gumpaste(Fondant & Tylose mixture) and let her dry for 2 days before I painted on the face and added hair.

Hope this helps?

that does help. i would never have thought of making a mold of the barbies face. I will need to try this, the barbies arent that large my daughter wants them with the castle cake I am doing and I really dont want to make the dolls out of cake as well.