My version:

Reference images:

Analysis (whoo, scientific): Shmi only has one hairstyle. It looks like the hair is pulled back straight into a braid without tieing it first. Then the braid is coiled around into a bun that wraps around the left side of the head only. This would seem like it'd be uncomfortable, since the weight is unevenly distributed, but then a lot of the prequel hairstyles aren't comfortable. No fasteners are visible.

Directions: Braid all of your hair without tieing it off first. The best way to do that and still keep it straight is to divide your hair into three sections and braid straight down the first few inches, with your arms over your head rather than pulling the hair around to your shoulder. Once you've got it started straight, then you can pull it around to finish braiding. Then coil the hair around into the bun, folding it to the left and pinning it very securely. That's it!