Alternating Scissor Jump Tutorial

Place one foot flat on the ground and the back a couple feet.
Descend down into a lunge where your front foot remains flat on the ground and your heel of the back leg comes up. During this motion try to keep your upper body straight up and down as much as possible. Back knee should come close to the ground.
Push through your front foot as hard as possible to jump as high as you can.
While in the air switch legs
Land back on the floor with your legs now switched and immediately repeat.
This exercise is normally done by alternating legs, but could also be done by doing continuous reps on one leg and then switching.

Keep your front foot flat on the ground so you can push through your entire foot and not just your toes.
Take your time as you land and jump again to make sure your body is set properly, but the goal is to move continuously without stopping.
Look straight ahead. Looking down will likely cause your shoulders to slouch down.

Pushing through your front toes opposed to whole foot.
Not pushing as hard as possible. Focus should always be to jump as high as possible.
Not going all the way down, or banging your knee against the ground. The back knee should hover close to the ground without touching.