For 30 years I have practiced only one technique. It has worked every time against everyone I have used it on, from little old ladies pushing shopping carts to terrorist warriors:
Make a blade hand, strike the enemy on the back of the neck and yell, "Karate Chop!" They drop like a ton of bricks and are out like a light for at least the rest of the movie....er I mean, day!
Works every time it's tried once you have perfected the technique, which takes 12 hrs a day practice, every day, for a minimum of 20 years. If you skip a day, you have to start over from day one and start counting from 0.