1. Speed. Weightlifting movements are dynamic. Think of moving fast and you will move fast. 2. Efficiency. Moving efficient means using adequate (not excessive) effort to fulfil your purpose (i.e. moving a heavy-ass inanimate object off the ground).
3. Patience. Hitting positions is key to allowing efficiency to occur. So getting to the right positions require patience to hold your posture till the right position is hit.
4. Strength. With the previous point, being patient require strength to keep posture till the right positions are achieved.
5. Legs. The ones that do all the work in the movements are the legs.
6. Not just hips. Weightlifting movements are similar to a kettlebell swing. But they are NOT a kettlebell swing. Concentrating too much on the hips creates unnecessary horizontal displacement.
7. Knees. This is a continuation of the previous two points. Think of moving your knees and your quads get involved. Quads are called knee extensors for a reason. Enough said.
8. Speed is developed from the start to overcome inertia. Creating momentum from the start is critical.
9. With adequate speed (again, not excessive), more acceleration can be applied onto the bar during the second pull. Not enough speed and you need to accelerate it faster in a shorter period of time.
10. Bar should move in close proximity from your body. But this does not mean you drag or pull it in, which would result in wrong positions being met.
11. Weight distribution should always be within your feet and as centered as possible.
12. Thinking about your arms should only occur at the receiving position (i.e. fully extended in the snatch, elbows bent and tight in the clean).
13. Control/Composure. The more frustrated or tensed you are or the more you have in your mind, the lesser the ability to think properly and focus on the right things (stick to two things: read my article on cueing).
14. Lift how your body allows you to lift. Leverage is dependent on your body segments and the levers they create. Not how you set up or move like Dmitry Klokov or Lu Xiaojun.
15. Don't bother arguing which pulling style is more superior or which country's system is crap to develop weightlifters. You do what you can and what suits your body to lift the most weight possible.
At the end of the day, weightlifting is heavily based on science/physics. If not, how do we get to explain so many details regarding the movement?
Simple enough? Image from Olympic Weightlifting Resource
The Training Geek