In our area there was a story in our paper about a tiny, 104yr old lady. This guy rang her door bell. when she opened the door he pushed in and she grabbed his privates and twisted them hard as she could. That kept him writhing on the floor till the cops could get there. I actually never would have thought to grab there and twist. Bet it would get their attention.
I took Judo classes many years ago. Judo is throwing/grappeling techniques. You use the other persons weight against them. You get them off balance and pull them or push them as you stick out a foot.
You can also hit them in the throat hard as you can with your fist and that will leave them gasping till you can get away. You can push hard against one shoulder and at the same time kick their feet out from under them. That gives you time to get away.