Naturally the best time to strike is when you have the element surprise, but that isn't always an option. In combat test your opponent steadily observing their stance and movements. Undoubtedly they will mess up and put too much weight on a foot slowing them down, over extend, become predictable, and so on. Stay light footed wary of your own stance, be tight in your movements, and mix up your moves. Try stepping into a cross block and unleash devastating attacks or continue the block into a throw or pin. Always keep in mind your own limits and fight accordingly. If an opponent has more endurance use more of his movements against them. Fighting lager opponents make them work by using the sweeping cross block to burn them out and quickly strike from behind.