Shaping those pleats

To make regular pleats, as in your "sexy-schoolgirl" costume skirt, you fold the fabric into "Z" shapes and pin it together. For box pleats, you reverse the folds, following a Z with a reverse-Z, so you have wide pleats that fold under on both sides. It gives the skirt a "bi-directional" pleating, and a soft, flowing look to the skirt. And the "selvedge hem" makes it even softer, without looking like a kilt-pleat skirt.

(What about that collar? It came with a harem-girl costume I ordered from Yandy.com...)