Throw him off guard, scream, bite punch, scratch, run. Don't try to defeat him, just get away. Half of all rapes happen in the victim's home. Victims do not cause rape. It can happen to anyone.
Rapists tend to prey on women who look frightened, easily intimidated, or day dreaming.
Women are taught to be polite and might be reluctant to yell in case they've misread a situation. You've got to learn to trust your instincts. The faster you react to a situation the better your chance of getting away. Hang up on obscene phone calls, don't react to them. 1 out of 8 American women state they have been raped.