In the practice of judo, no matter how intense the match, one rule is paramount, when you throw an opponent you try to keep the person's head from hitting the mat. In self-defense, you could care less about protecting the attacker, and you may even ensure the attacker's head hits the ground first.
Check out the following link for animations of many throws: http://www.Judoinfo.com/animate.htm
Throw defenseIt is very difficult to throw an opponent. You must commit yourself to the throw and sometimes turn your back to the opponent or even fall yourself, which means you are sometimes in a vulnerable position. To complete a throw successfully, you must complete many movements successfully, which makes throwing difficult. Another difficulty in completing a throw is that it is relatively easy to block a throw.
For any attempted throw to be successful, the opponent must be off balance, you must keep your stability, and you must get your center of mass below the opponent's center of mass. Other factors need to be present, such as a firm, advantageous grip, and quick movement, but they are less important in actually getting the opponent to the ground. To block a throw, you must keep or regain your stability, upset the attacker's stability, or keep your center of mass level with or under the center of mass of the attacker.
When an opponent tries a throw where his or her back must be turned to you, a simple defense is to use a free hand to push against the bottom center of the opponent's back to push the hips forward. This upsets the opponent's stability and makes it almost impossible for him or her to lift you. If you bend your knees to lower your center of mass, you may defeat many attempts to throw you. Leaning backward will also shift your center of mass back to your advantage; however, if the opponent switches throws and goes for a backward throw, you will be vulnerable. You may also step around the pivot point of the throw so the opponent slips by you.
For a foot sweep to be successful, you must be caught in shifting your weight onto the foot to be swept. A foot sweep attempt may be defeated by lifting your foot out of the way or by shifting more weight onto the foot so it cannot be swept.