MMA Tip: Guillotine Choke
The Guillotine choke is a great submission to apply to an opponent as they are charging in at you with their head low as if they are trying to tackle you. You want to catch them and keep their head down and inside your armpit, wrap your arm and bicep around their head and then lock your arm up under their chin into the neck.
Once the grab is applied, you want to drop your hips and push them forward. Many people tend to try to lift up for the submission but that becomes a struggling game and you can spend a lot of precious time and give them a chance to escape. If you drop your hips down and push forward you are essentially collapsing their chin and choking them out.