The easiest article of clothing to sew, in my opinion, is a simple skirt with an elastic waist. Zippers and buttons can be hard to get just right, but an elastic waist also has the advantage of fitting you both on your skinny jeans days as well as on your fat jeans varieties. A skirt was the very first thing that I sewed when I was learning. It only took me a few hours to cut the fabric, sew the front to the back, hem the bottom and put the elastic in.