The half Nelson is a very common hold in wrestling. It is usually put on when both opponent's are on the mat but you can also use the same technique when you are stood up, so practice it from both positions.
The half Nelson is secured by passing the arm under your opponent's arm then way accross the back of his neck. This gives you a strong leverage, and by pushing your opponent's head to the mat you can work for an assistoing hold with your free hand.
This hold is not usually used alone to gain a fall but when used in a combination it can be a powerful factor in winning a match. (a strong half nelson with a crotch hold is very hard to break and usually means a fall) The half Nelson is used in no less than 20 combinations.
Practice this daily. It is very good for the neck muscles.
