Use one of the following techniques, depending on your situation.
The hook - This technique is useful if you're as strong as your opponent in either forearm strength, bicep strength, or both.
Curl inwards your wrist. This will extend your opponent's arm, but will require you to put a lot of bicep power in.
Maintain wrist contact throughout the match so that force is delivered through the wrists, rather than the hands.
Get your body (especially the shoulder) over your arm and keep your body and arm close together. Drag your opponent towards you as you push it down.
The top roll - This move is more about leverage than brute strength. You put pressure on your opponent's hand, forcing it open and making it more difficult for him to use his muscles.
Get your elbows close together. The resulting height gives you more of an advantage. Achieve as high a grip as possible on their hand.
As soon as you hear the word "go" pull your hand towards you, pulling your opponent’s hand away from their body. This can help you get a higher grip.In this technique you will pull your body back.
As you push their hand down, pull the opponent's wrist back. Their palm should rotate towards the ceiling.
Use one of the following techniques, depending on your situation. 
