From Simple Modern Sewing:
The A-line skirt is a very simple and basic style. It's also very flattering. You can make the simplest style just as it is or vary the pattern in small ways to create different silhouettes. You can also change the length of the skirts. Make long skirts for dressier occasions or mini versions to show off your legs. Widen the pattern piece and add elastic to the waist to create a gathered skirt with or without a drawstring tie.