There are many way to improve your kick and add more power to it. Improving and using the right weapon to kick is crucial. And since kicking is not the same to all martial arts because they use different techniques and moves, you have to know how Muay Thai fighters properly deliver kicks to the target.
The best weapon for Muay Thai Kick is your shin, not your foot. Remember this because you might see somewhere else like in movies that many times they use their feet to attack and that is very wrong. Your feet consist of many tiny bones that can be broken easily and kicking is a very hard contact. On the other hand, your shin is one big and strong bone. Think carefully which one you want to use for hitting the target? Which one will create more impact to your opponent?
Now you know what is the best weapon, then the move. The correct move to deliver a kick is to raise your leg up at the aforementioned angle with your foot point upward at about 45 degree angle which guarantee that your shin bone, not the muscle underneath it, will hit the target.
Practice the correct way of kicking. Prepare your shin by applying the Luminent oil or Nam Man Muay and use the leather padded shin guards. Practice the move repeatedly with the correct movement with a heavy bag or sparring partner with kick pads. Remember not to turn your feet down or horizontally to the ground.