I know this is an old tutorial but I was looking through it to see if I could find any tips I don't already know, and instead I have one to share!
Instead of cutting out two rectangles for the base of the skirt, I like to cut out one long one. I try to study the way my clothes from Baby are sewn in order to figure out how I can make mine better, and one thing I noticed is that on the two rectangle skirts I have from them only have one side seam because they're sewn from one long rectangle. This is especially great for larger prints because you don't have to try to match them up at two seams, just one!
You taught me something too! The "multiply your waist by 3.25" part. That's a great tip. I got within one inch of the length I was using for myself and so that's how Baby apparently makes them.