How do I set up the rear naked choke?

Getting the arm under the chin is the hardest part of the rear naked choke. Experienced opponents will tuck their chin and fight your hands aggressively. To create openings, threaten other submissions first. An armbar threat from back control forces them to bring their hands up, momentarily exposing the neck. Collar choke attempts in gi achieve the same effect. Another approach is the short choke, where you use your forearm across their face to pry the chin up before sliding under. Hand fighting is a skill that requires extensive practice. Use your free hand to strip their defensive grips while your choking arm works toward the neck. Once under the chin, the finishing mechanics matter greatly. Your choking arm bicep should be on one side of the neck and your forearm on the other, compressing the carotid arteries. The free hand goes behind their head creating a figure-four lock. Squeeze by expanding your chest and pulling your elbows toward each other rather than just squeezing with your arms.