I find that making a mock-up in graph paper really helps.

With all the pleats, it's a little hard to keep track of exactly how much fabric you'll need, especially if you have to piece together two lengths and don't want the seam to show by making it an inside pleat edge...

Plus I can't tell you how many times I screwed up my math on pleats because of the first and last ones. I still can't wrap my head around the formula, but I can cut out a tiny kilt from graph paper to scale, no problem.