Establish a dominate position by bringing your knees under your opponents armpits to isolate both arms. In live situations though with your opponent defending you will probably be only able to isolate one arm. Turn your body slightly, facing the arm you want to isolate while maintaining mount. Take head and arm control by pushing your opponents arm past your head. Once secured, give up mount by going Reverse Knee on Belly, drop to a sprawled side control position, and rotate your body to tighten the choke.
1) Head & Arm Control
2) Head & Arm Choke