The most important thing to remember about jumping (either with both legs or one) is to always keep the knees in line with the ankles and to always make sure you bend your knees upon landing. If leaping from one leg, put a good amount of awareness on the down step of the hind leg. Same applies with hopping. Observe and copy the various animal jumps (such as frogs, cats, and rabbits). All jumps can end with any number of falls.
Exercise 1: Butoh Jump Rope
Jump rope and make great use of reduction & regeneration by X
Exercise 2: Maximum Excitement
Since high excitement is associated with jumping, take excited jumping into the level of absurd.
Exercise 3: Bouncy Ball
Mimic the ball as it decreases its bounce.