You're a good sister. First I think it's important to educate her about sex and then explain the dangers of having it too young. Boys that age basically want sex, with little regard for the young woman. Advise her to stay away from relationships with boys, becasue they're so fickle and this wears on a girls self esteem. Get her involved in physical exercise - it's well known young women who exercise or belong to a team, have better self esteem. Have her look at http://www.dove.ca/en/ website and click on 'campaign for real beauty' - about how the beauty industry falsely put out these unrealistic images that don't really exist in real life. Encourage her to be the best she can be and not to compare herself to those images. Emphasis focusing on her education and taking care of herself, so she'll never have to depend on a man financially. You can also encourage her to have her own mind and don't be afraid to stand up and say "no" or walk away from uncomfortable situations - drugs, alcohol, sex. These are things I'm teaching my daughters about. Best of luck