Might as well share another neat trick I learned elsewhere....

Apparently, if you're in their guard and they have you in a guillotine, I'm told that if you force your head DOWN into their armpit, and push the top of your head against the ground, it actually alleviates the "cranking" your opponent does, allowing you to worry about getting your hand in there, or whatever else you need to do to get out of there. Sounds like a neat trick, and I've heard good stories about it from 4 or 5 people.