Guarding our eyes for Girls

Hello, 

1. It is permitted for a woman to look at a man, provided that this does not cause forbidden thoughts. See Yabia Omer, part 1, Orach Chaim, siman 6, seif 5, and the addendum there, which states that there is no prohibition for a woman to look at a handsome man. In any case, it is explained in Sefer HaChinuch, mitzvah 188, that women are also commanded not to have improper thoughts about men. Therefore, it is obvious that if looking causes her forbidden thoughts, it is forbidden. 

2. There is no halachic prohibition for a woman to see another immodest woman, but this may be harmful and weaken sensitivity in matters of modesty. See Sefer Chinuch Yisrael, part 1, page 302. 

With blessing, Hillel Meirs