Many different factors come into play during a game of mercy. Strength, speed, stamina, flexibility, and leverage are all crucial to winning
Strengthen your wrists and fingers. Grip strengtheners, finger push-up, and weight lifting can all help you win at mercy.
Grasp your opponent's hands as hard as you can. If you can squeeze hard enough, you can weaken his grip. This will allow you to more effectively leverage your wrists against him, bending his back and winning the game.
If you are tall or have long arms, use your advantage in leverage. Raising your arms up high will make it difficult for your opponent to use his strength against you. A taller player can often win using this strategy even if he is weaker.
If you are shorter, keep the game low and in front of you.Vigorously push down and forward, bending your opponent's wrists.
If your opponent quickly attacks, draw him off balance. He will be expecting you to resist him. If you back up quickly instead, he will stumble. Then quickly counterattack.
Set the rules of the game. For example, you can push hard with one hand while turning away from the other hand, making your opponent defend on that side, then quickly revers and attack from the other side. Doing this gives you the initiative and forces your opponent to address you.
Some people view pushing with your chest as fair, whereas some think it is cheating. If this strategy is considered fair in your circle, use it. It is an easy way to push your opponent off balance. A strong opponent with weak footing is still easy to overcome.