So to answer Joseph directly, I disagree with two attitudes expressed in the OP:
(1) The main issue is not a lack of awareness. People know and understand the issues. But it’s difficult. More difficult, apparently, than you or I or any male can appreciate. There’s a Yetzer Hara. People need a wake-up call to encourage them to take any upwards leap. Provide the correct inspiration, and you’ll see a positive response.
(2) “Forcing the decorum” is a battle not worth fighting. It would be much more effective and practical (and probably ethical, but that’s exactly the discussion you wanted to inspire) to enthuse them about tznius without having to fight against them.
If the issue is awareness – just giving a list of facts is pointless. Just giving a shiur chizuk is also pointless. You’ll notice that chizzuk by nature dissipates. They used to say in Yeshiva “A good mussar shmuz lasts until supper”. The trick is to get induce a euphoric-chizuk mood, and attempt to force a kabbalah whilst they are still on a high. (Think הרואה סוטה בקלקולה יזיר עצמו מן היין. Specifically after seeing a Nes Nigleh in the Beis Hamikdash, which is the most inspirational sight possible, you should make a kabbalah.) Then even when the inspiration dissolves, the kabbalah will hopefully last somewhat.
I once heard from an International speaker that the only way to give a good Internet Asifa (he has spoken in many) is “15 Minutes ‘Kol Nidrei’, 15 Minutes of Information, followed by 20 Minutes of ‘Neila'”.