Before you start, make sure to use hot hair rollers to gently curl the hair and get ready some bobby pins, a skinny ponytail holder, and a flexible hold hairspray.
Once the hot hair rollers have cooled, you can remove them and gently shake the hair to make the curls come slightly undone. You can also pull your fingers through the hair to get that loose curl effect.
Pull the hair into a very loose ponytail and secure it with the ponytail holder. Then roll the hair up and under and use bobby pins to secure the hair in place. The effect should be natural, so don't roll-up the hair too high or too tight. Add a touch of hairspray for texture and movement and you're ready to shine with your new cool medium length hair.