There is no perfect way to protect yourself against rape, but the following have worked for many people...
Know you have the right to set your own sexual limits. You may have different limits with different people; your limits may change. It’s a good idea to know what you want or don’t want so that you are the one who decides for yourself.
It’s up to you to communicate your limits. Get them across to the other person. E.S.P. doesn’t work.
Trust your feelings. If you feel that you are being pressured into unwanted sex, you’re right.
Pay attention to behavior that doesn’t seem right.
Someone who “Power stares” — looking through you or down at you.
Someone who blocks your way.
Someone speaking in a way or acting as if they know you more intimately than they do.
Someone who grabs you or pushes you to get their way.
Someone who doesn’t listen or disregards what you are saying.
Get angry when someone does something to you that you don’t want.
Act immediately with some kind of negative response. (You may want to practice this alone or with friends.)
Stand up for yourself — it’s ok to be rude to someone who is sexually pressuring you, even if it hurts their feelings. After all, they’re not paying attention to your feelings.