Use the Pendulum Principle
These are what you might call double-duty karate techniques. They combine defence and offense, the timing flowing from block into attack, then into block again. If you think of a pendulum, this principle becomes clear. Swinging left to right, it never stays in one place, always moving back and forth. What goes up, must come down: very much like the motion of the leg during a high kick. So when you see your opponent move into a high kick, you can estimate where his foot has to come down, and strike there. Itís one way to be sure your kick will land.
(At first, practice with kicks in low positions, then widen your repertoire.)
At the same time, while your opponentís leg is up there in the air, take the opportunity to punch or kick him on the body or head. You can do this easily if you initiate your attack at the precise moment you block his. Timing is all-important. While you are blocking your opponentís attacks, you should be returning the same to him, punch-for-punch, kick for kick. Speed and timing are crucial. Unfortunately these are things you have to learn not through theory, but with your body