I've done Pilates For Dummies, and it was a great start, hard at first though. But I pushed thru it and my back felt better, and I held my body higher. It was great. I then moved on to Winsor Pilates, I also really enjoyed that, but you have to be pretty limber and definitely on the thinner side to do all those weird positions. Definitely for beginners I would suggest Pilates For Dummies
-Aimee