Marcelo shows how he goes for a Guillotine-Choke while inside a Half-Guard: When you go for your opponent's neck and wrap your arm around their head, make sure to block your opponent from securing an under-hook by keeping your hand and elbow inside and posting against their biceps. When your wrists connect across their throat, immediately close the short distance and clasp your hands together with a Seat-Belt Grip (a.k.a Ball-n-Socket Grip, Reverse Cup-n-Saucer, et al.). Bring your weight forward as if approaching the mount by placing your forehead on the mat and yanking your elbow free from your opponent's defenses. If you cannot readily make your hands connect together, use your ribs to help cover your opponent's arm from freely coming up to pull away your choking-arm. If you have a clean bite on your opponent's neck but they managed to acquire a tight under-hook, use your hand to help push it down and low enough so that you can connect your hands together for the squeeze. Howe one approaches a finish with the Guillotine-Choke is largely dependent on the responses of your opponent; some may prove difficult in the beginning and fade towards the end, while others may let you enter easily but fight hard against your throttling mechanics.