Seated Box Jumps
To begin this plyo exercise, start seated on a box. (The box should make your thighs approximately parallel to the ground. Adjust the height as necessary based on your level.) Pick feet up off the ground and slam them down while continuing into a full vertical jump. Be sure to completely extend your body at the top. Jump up onto a box that is a couple feet in front of you.
Start off with a lower box to jump on and as you progress you can increase the height of the box. Be sure to land in a good squat position and NOT on your tip-toes.