Modesty
“What about the teenage girls living in an environment where they are felt left out when tznius. and part of the club when dressed not tznius.”
It can be very difficult. The way to overcome it is by taking pride in dressing tzniusdik. People respect and trust those who hold true to their values even when it differs from
the crowd. The way to build up pride is by learning about the positive (and negative but focus on the positive) until it becomes so much a part of you that it is who you are.
When I was in high school we had a wonderful curriculum where we learned how tznius is the Jewish culture, how it brings to kedusha etc. After the general introduction we went into the specific categories of how it applies (and the power of) sight, music, and dress.
One of my favourite classes. Wish all high schools taught this.