Imagine the Guillotine being a paper cutter. With your partner’s neck being the sheet of paper, your shoulder being the base of the paper cutter and your forearm being the knife of the paper cutter.
The blade of the paper cutter needs to go directly towards the base for the paper to cut. A common mistake is to extend back on the Guillotine. While this may work, mechanically it’s flawed with many of your partners just puling their head out. You want to see a shearing motion with your forearm towards your shoulder.
Same idea as a regular Guillotine but you have one of your partner’s arms encircled within your grip. You’re still trying to shear your partner’s neck much like a sheet of paper in a paper cutter.
Rear Naked Choke
For the Rear Naked Choke, you’re turning your forearms into a paper cutter.
The forearm behind your partner’s neck is the base of the paper cutter while your forearm in front of your partner’s neck is the blade of the paper cutter.
A common mistake is to have your forearm behind your partner’s head. This is wrong as you can’t get your forearms acting like a pair of scissors.