I sewed up a sundress for my Kidz and Cats doll out of a shirt. The original top already had the shirring, so all I had to do was cut a rectangle and sew a seam on one side to make a tube. The original top also had strings, which I cut and sewed to the sundress to make a halter top style. I made a similar dress for my American Girl Doll here. You can read about the matching flower headband in the pictures below there as well.
For this bun, I put the headband on first. Afterwards, I took a section on each side from near the ear and braided it. I then had two braids on each side, and a large lock of hair in the middle. middle section of hair I twisted up into bun, securing it as I went with bobby pins. Once I had the bun in place, I wrapped the braids around and pinned them.