You might think that Brazilian Jiu Jitsu is not that different from other martial arts but this is not true. While other styles teach you to fight well while you are standing, this one will help you learn how to subdue an opponent when you are on the ground.
If you are overpowered by your opponent, fall to the ground because this will make him think that he owns you. This is the best position for one Brazilian Jiu Jitsu technique known as the guard.
What you are trying to do here is keep your opponent down using your legs so you prevent him from hitting, pinning or mounting you.
To be in the dominant position, try the arm drag to arm bar maneuver by pulling their sleeves in one hand towards you.
Hook one hand under the opponents leg and control his head with the other hand. Move your hips out to create space and circle your hand to the front of your opponents face then swing your leg over your opponents face. Arch a little to apply the arm bar as this is the only way to trap your opponents arm by keeping this tight to your body using your tricep.
When this is achieved, you can do whatever you want with them like punch them in the chest....