Since I am specializing in making flamenco dresses I finish hardly any dress or skirt without "volantes", ie. frills or ruffles.
I often get asked what types of ruffles there are and how to make them. There are two basic types of ruffles: Circular ruffles and gathered ruffles.
Circular ruffles, as the name suggests, are cut from a circle which has a smaller circle cut out of the middle. The size difference between the two circles determine the amount of volume the ruffle will have. A small inner circle creates a full ruffle whereas a larger inner circle achieves a more wavy, softer ruffle.
Gathered ruffles are cut from one or more long stripes of fabric where one large side is gathered. Obviously, the more you gather the more volume the ruffle will have and the longer your fabric strip needs to be in order to get to the desired length of the ruffle. Ususally you'll want to cut a fabric strip 1.5 to 2 times longer than the ruffle length.
For full instructions check out the tutorial => http://budurl.com/ruffles
Now let your imagination go wild and have fun!