Most NBA players have vertical jumps in the 28 - 34 inch range. To get your best vertical jump it is necessary to do both strength and power training.
Strength exercises include slow, controlled movements like squats, lunges and step ups and power exercises require explosive, quick moves like those need for plyometrics and power cleans. Plyometrics are explosive bounding, hopping and jumping drills. They blend strength and speed. Finally, practicing maximum vertical jump will increase vertical jump.
Source:
Bill Foran, Strength and Conditioning Coach, Miami Heat. Vertical Jump - How to Jump Higher. [http://www.thebasketballzone.com/images/hints&tips/Vertical%20Jump%20-%20How%20to%20Jump%20Higher.pdf]. Accessed 10, 2009.
