What you will need:
Small Barrel Curling Iron or Ringlet Curlers
Step 1: Brush your hair and make it smooth. Part your head on the left side and spray the par with hair spray. Clip up the top half of your hair and work in layers. With this look, Hermione's hair is really curly, so the more perm-esque you go, the better it will look.
Step 2: Grab a 1 inch section of you hair and wrap it around the curling iron or curler. If using a curling iron, a good way to keep the ringlet solid, is to apply a little bit of hairspray to it while its on the iron. Continue to work around the base of your head until the layer is complete. Apply some more hairspray to it. Now unclip the excess hair and section out a new layer. Repeat this step till it is all curled.
Step 3: Now that all the curls are completed, apply another quick layer of hairspray so the ringlets stay in place. Bounce the curls with your hands to give them a nice bounce as well as some work with the weight of your hair. Finish off the look by perfecting your part and work with any stray curls. If you want to bobby pin some to the side, Hermione's hair has that is some of her looks with this hair style.