So begin in your opponents half guard with your right leg stuck in between his legs
. Have your left arm wrapped around under his head and keep your right arm under his left arm obtaining the under hook. Having the under hook in this position is very crucial. Also make sure you are putting your weight on him with chest to chest so that there is no space between your hips your opponent to be able to move.
You may want to grab a hold of the back of his Bjj Gi with your left arm and with your right arm take his Bjj Gi lapel out from under his belt. Now with his Bjj Gi lapel or collar feed it under his left armpit to your left hand. Be sure to pull his Bjj Gi collar tight to give yourself optimum leverage and make sure there is no slack. Follow this by pressing your left shoulder onto the right side of your opponents face making him completely looking to the left and not be able to look to the right with his head. If his head cannot look a certain way, than his body cannot go that way. This action combined with wrapping your opponents Bjj Gi will prevent him from facing you and escaping his hips.
Next, plant your right foot flat on the floor and slide it upwards towards your opponents butt. Then grab and firmly grip your opponents left Jiu Jitsu Gi pant leg and switch your base so that your left knee is against your opponents side. Keep in mind that while you are doing this whole move you must still be in control of his Bjj Gi so that he cannot escape this position.
At this point you should have the leverage and control. With your grip on his Gi pants push your opponents left leg outward to simply remove your right leg from in between his legs and base out. From here just simply stay chest on chest and keep control of his Bjj Gi and be sure to maintain a good solid side control.