A famous (female) lecturer once told me that she has had many tamidos over the years who went from wearing pants, etc. to full yeshivishe woman garb, due in large part to her classes. What does she do? She never, ever, mentions tznius or that people aren’t keepin it. She focuses on a woman’s job and role as an akeres habayis, the center of her children’s and her family’s life, and her connection to Hashem and to yiddishkeit. When people hear the beauty of this messae, they naturally want to act the role that they realize they are filling.