Well, first and foremost stretch your legs, whether you kick high or low, this will help reduce the possibility of injury and allow your legs to be more pliable and loose.
Keep structural alignment, you cannot achieve the most efficient power unless the technique is good. (Your hips my friend, your hips...) Also, balance is necessary for the best power.
Train actually kicking something. Training kicks in the air is fine, and I do it all the time, but if you have never made contact with a kick, you won't be likely to do it well the first time. Practice kicking pads, bags, whatever...all the while staying loose until the point of impact just as a punch.
*remember to bring the leg back quickly and control the kick. Don't let the kick control you.
"I don't know if anyone is known with the art of "sitting on your couch" here, but in my eyes it is also to be a martial art.
It is the art of avoiding dangerous situations. It helps you to avoid a dangerous situation by not actually being there. So lets say there is a dangerous situation going on somewhere other than your couch. You are safely seated on your couch so you have in a nutshell "difused" the situation."