What is the most important aspect in achieving a high vertical jump? Most athletes and even experts have never really come around to finding a very precise and accurate answer to that question.  A good jump is a combination of several factors which when balanced, can grant one the ability to be suspended amid air for the longest time.  The first is the force produced by the legs that thrusts the body off the ground.  The second is the agility and the flexibility of the legs and the third is the speed at which the body leaves the ground.

If you need to learn what exercise you need to do to get the best balance of these aspects, I would suggest you find a good jump manual.  The jump manual of your choice must be easy to follow, well-illustrated and practical.  Such a manual will be invaluable in giving you the high vertical jump you always wanted.