Here's another fun Pinterest one that has been floating around. It's really simple and has a beautiful look:
I have to admit that I LOVE this with the blonde highlights in this girl's hair!
Start the style by sectioning the hair out into 3 horizontal sections and secure each section with an elastic. *You can choose to leave some hair out like in the example which you can curl for a more formal look.
Now take each of your three ponytails and create a 3-Strand Braid out of them - securing each of your braids with an elastic at the bottom. Starting with your top braid, wrap it around it's elastic so that you form a bun and then secure the ends of your braid with bobby pins by tucking them underneath he bun.
The length of your princess's hair will determine the size of your bun. If she has shorter hair, you can keep your braids looser to give the bun a more full look. Add a flower to the side as an accent if you like and the hairstyle is complete!