For my daughter's solo tap performance, she needed a pettiskirt. I wasn't sure what it was so I googled "pedi skirt" and came up with this very helpful tutorial from Ashley http://www.makeit-loveit.com/2010/07/full-and-fluffy-pettiskirt.html Read it for the full instructions because I only include here how I altered the size and materials used.
Following Ashley's tip of tightening the top tension on the sewing machine (7-10) and elongating the stitch length to 5, I was able to ruffle very easily. In order to adjust the ruffle I left very long thread ends and ruffled a few yards at a time. I broke it into four sections.
http://www.afc-express.com/ The top tier of chiffon was 6 yards and the bottom was 12 yards. For both skirt layers I used 36 yards. For the waistband I used a stretch satin that was very shiny. My daughter's waist is 23.5 inches so I cut the satin 8" x 47".