If churches started a class on modesty, nearly every person at those churches could benefit. Men need less provoking of their imaginations, and women need the emphasis on godly character rather than great bodies and expensive fashions. Children could also use more godly role models at church.
But why would such a class even be needed? By the looks of the way teen girls and adult women in our churches dress, someone is going to have to coach them on living modestly. It's been my experience when a leader requests that women wear something modest--like, on a mission trip--even well-meaning women still wear provocative clothes or behave immodestly, like bending over at the waist and not at the knees. Therefore, women must not know what modesty is.
For a modesty 101 class to succeed, the senior pastor, or director of the appropriate department, needs to support it wholeheartedly. If the leadership isn't behind this venture, it won't likely work. But convincing godly leaders of the need to address the immodesty problem among confessing Christians shouldn't take too much effort. Once leadership is on board, find the teachers. Ladies who know the true meaning of modesty and who live it consistently would be the most likely candidates to teach this class. Even finding these teachers could turn into a serious search, but hopefully there are females in a given evangelical church who exemplify the virtues of modesty. If they know Christ and have the ability to teach, God could use them greatly to usher a church into holier living.
I don't think I need to give ladies tips on how to go about rounding up people for this class--most women know how to get other women together. Whether it be in a home or in a church room, a one-time session or a series, a respected lady who teaches other women how to dress non-provocatively and how to dress and carry themselves in a way that glorifies Christ instead of a woman's body, is much needed today. Eventually, classes like this would grow in popularity, and positive peer pressure would build for all the women of a church to attend at some point. As long as a modesty class like this doesn't grow into a snobs-club, which biblical teaching on modesty will deflate, such discipleship would only help the local church.
Some Women Call it Fashion
A Word to Women on Modesty (Part 6): How You Sit, Bend, and Carry Yourself
Modesty: General link