0GorframBest Answer 9 years ago ReplyUpvoteZippers are always tricky, and zipper flies are among the worst. Hopefully yo're already familiar with putting in simpler zippers(?), and you're working from a pattern which gives you some help in the instructions(?). The best general strategy I've found is to go slow, be careful, be thorough, and to take it easy. I have my best luck with zippers when I first pin, then hand baste before sewing by machine. The basting step may not seem necessary, but can save time & grief in the long run. Take frequent breaks, especially if you find yourself cursing a lot :). Putting the work aside overnight and starting fresh the next day is sometimes the best thing you can do, and a good seam ripper is an essential tool. And, of course, YZMV (Your Zipper May Vary).