I've been working on a beautiful crochet skirt for my daughter. She is a size 4t and the pattern is so simple. I chain 90 stitches then single crochet in rounds. I never join the beginning waistband because I like to add buttons when the skirt is finished. After I work the waistband to the thickness I like, I increase every five stitches. 90/5 =18, so my increases is just two sc, in each fifth stitch. This makes the skirt have a very nice puff to it, or fullness.
Then, I just let my imagination go to work, and if I need to increase, I just increase on every fifth stitch. My patterns never have more of a format than what I've listed.