There is a video on The Quilt Show "Sally Collins Teaches Precision Piecing" that I found very helpful. She also has a book. I have already watched the video twice and will probably do so several more times. Lots of good information. It will be available either until or through September. You have to join to watch most of the videos but I think I have already learned enough in a month to pay for the membership. It was recommended by someone here on the board.