One thing you can try is working the snatch from the top down, starting from the hang above the knees then eventually adding in the preceding steps (hang below the knee, floor) as you feel comfortable with each segment of the lift. The intent is to help you get comfortable with your 2nd pull without having to worry about all the stuff that comes before it
Stand with the bar using your snatch grip, then slowly slide it down to above knee level -- while doing so, make sure to maintain a tight lower back and big chest, push your butt back, keep the bar close to body all the while keeping the weight on the heels. When the bar is just above knee level, snatch it (for some reason, the cue of pushing myself off the floor clicked more with me than the "jump" cue, but they're both intended to accomplish the same thing). That's how my coach had me start out and I think Dan John terms these 'RDL Snatches'
As said before, you'll eventually want to add in the preceding stages of the lift (below the knee, floor) to get comfortable with the transitions.
P.S. there's a great video of a 3 position snatch in the Exercises section of this website.