There are a lot of people out there teaching the Olympic lifts in a number of venues. CrossFit, college weight rooms, powerlifting gyms, and personal training studios are all utilizing these fun and powerful lifts for strength and power development and competition. However, I do see a lot of glaring form faults from time to time in the execution of these lifts that are easily fixed and make a huge difference in how much weight the lifter can move.
The most important aspect of the Olympic lifts is the powerful extension of the posterior chain. This mainly originates from the hips and is often mistaken for a jump. However, we don't want to move ourselves AND the bar, just the bar. Driving through the heels as long as possible will ensure that more power is transferred to the bar alone. Driving through the heels also ensures that our center of gravity stays over our heels and not our toes. You can see that although all of these lifters are on their toes, their center of gravity is still over their heels. This is because they aren't jumping. Their heels leaving the floor is the result of violent hip extension. Driving through the heels also keeps the bar close to the midline and allows us to exert maximal force on the bar with powerful hip extension. Most people get this right.
Next time you're cleaning or snatching and it doesn't feel quite right, have someone watch you and/or take a video. If it doesn't look like the guys and gals in these pictures, try it, you might find you have a lot more power in the tank when you extend your entire posterior chain instead of just the hips.