Do you find that your feet never quite end up where they need to be when you snatch or clean? For example, they're always too far behind you? Try actively lifting your feet and replacing them flat on the platform, focusing on landing on the whole foot, not the balls of the feet, and directly under the bar. You might be surprised how much it improves your balance and position when receiving the lift.
Now before you go and tattle on me, I'm not telling you to lift your feet way up into the air. I'm saying make them separate from the platform enough that you can replace them flat and aggressively in the correct location. This doesn't require much air space, but it does require you be active and aggressive and precise.
If you have trouble kicking your feet back and landing on the balls of the feet, try thinking of lifting your knees rather than lifting your feet, and of sitting your hips straight down with a vertical torso rather than pulling your hips back after you finish your extension.
Ask Greg: Jumping in the Snatch
Weightlifting Technique - With Evidence