I've found snatches from a dead hang/full extension to be helpful.
Start standing up with a snatch grip, bar hanging at waist height or wherever your grip lets it hang I suppose, light light weight at first (<50%). Give it a little toe/shrug action and drop under. Bar isn't coming up nearly as high as you're used to, so you've gotta drop fast or miss it. I find that a lot of times, most of my thought process is consumed by getting a good 2nd pull, that I can't keep it together for a quick 3rd pull.