Say your opponent is coming in with a hook; pretty common. Of course, the first step is always going to be to get out of the way as soon as possible. If your opponent is taller than you, or if roughly the same height, this could work.
When someone throws a hook, which is one of the most common attacks you will get if you’re ever attacked…God forbid you are…martial artists will always instruct you to clear the path one way or another. That means moving to the side then striking back, or in this case: ducking. Ducking is an undervalued skill that anyone can do, even people who don’t have a lot of weight or strength. And if you’re clever with it, you’re going to find out that you can strike your opponent wherever he or she is vulnerable.
In this case, the opponent throws a high upper hook to the head, the most common you find in the streets or in unfriendly parts of town. The first step is to actively come in and close the gap while you duck (that is, step in and lower yourself significantly). Have both your hands ready. Your opponent is going to miss his or her hook, and that’s expected. However, your opponent is also going to try and strike you with their other hand. Using your right elbow, block that hand as the strike comes in, or press that hand against his or her body to prevent movement for a brief second. This way, both of the person’s hands are out of range to damage you. The high hook is probably passing over what would have been your head. Your right, or left, hand is going to be the blocking hand. But this naturally means you have on hand open. You can punch your opponent’s side with this as you’re aiming for a sideshot with these things. By doing so, in the case illustrated, I actively blocked while I punched the armpit of my opponent, raising his attacking swing in the process.
That gets you out of the clearing, and you can finish your opponent off using a kick, some more punches, etc. But at this point he or she is probably not going to pose a problem anymore.