I think the first step is clear and accurate sexual education for boys and girls starting at an early age. Most experts say if your child hasn't begun asking the basic questions by age 5 then start telling them. Always use correct terminology, not slang so as to develop respect for oneself and body parts. The term "boob" is not allowed in my house. It is derogatory. However we will happily have clear and accurate discussions relating to sexuality at the dinner table. It's not a secret or something shameful to discuss but it needs to be respectful and not giggled over.
Also while abstinence is certainly desirable numerous studies show that abstinence only education is not effective. Girls and boys need correct language and tools and practice in what to do or say. Also abstinence only models of education put the blame and guilt on the the girl and not the boy. And they don't cover abuse issues much at all.
My kids have both participated in Our Whole Lives Sex ed classes through the UUA. http://www.uua.org/religiouseducatio...cula/ourwhole/
These classes are accurate and informative. The instructors must be trained prior to teaching. My son always says he knows everything that they teach in health class at school already because of these classes. It also is good because he is aware if kids are saying things that are incorrect. Also health class at school doesn't cover much. The classes help develop an understanding that what you see in media images does not reflect reality. Abuse protection and knowledge is also and important component.
My son has been informed that if he gets a girl pregnant not only her life but his will change. I will see to it that he is fully responsible even if it means the loss of or delay of a much sought after education. It's particularly important to teach boys respect of all people and women and to help girls have positive self esteem and stand up for themselves.
While the rape and sexual harassment is presented in a sexual manner the crux of the problems is lack of respect and violence against another person. Violence is just not okay. In addition to numerous sexual messages in our society we also have numerous violent messages all making it somehow look okay.
It is all a complex problem.