Life isn't fair – neither should be your Jiu jitsu: Fair play is a wonderful thing but not in Jiu jitsu. Your game is to create an uneven playing field using mechanics and tactics that put your opponent at a disadvantage that makes your very likely. One of the best ways to begin doing this is to trap opponents arms. One of the quickest ways to render a human helpless is to pin his arms – that's why the first thing police officers do with unruly suspects is handcuff them. It's a simple way of making dangerous harmless. So too when you do it it in Jiu jitsu. If you can trap an arm and pin it down you can render a strong opponent helpless. Our time to do this is when you're behind someone. It makes the task of strangulation so much easier. Don't be satisfied with the rear mount – go further and trap an arm whenever (and if you know what your doing it usually is possible ). Defending your is difficult enough with two hands – with only one (the other one trapped) is VERY difficult indeed. Make a serious study of UNFAIRNESS and you will have advanced your understanding of the true nature of Jiu jitsu