Some points in kicking in the martial arts, reviewed from a recent class:
We start with the base leg, making sure we never lift the base foot of the ground, no lifting the heel up to kick, making sure there is some bend in the knee of the base leg to help with balance.
Freedom of the kicking leg. The ability to kick the target and place the kicking leg back down on the ground anywhere we want. Control over our own balance during the kicking process.
Making sure the spine (back) is straight, making sure one is not leaning into the kick to hit the target- which means the target is out of distance.
Hands up to protect, and be ready to take ukemi if the kick misses or is countered.