The problem with hilchos tznius is that every community defines things differently. My Rabbi holds that the collarbone is not an issue and can be shown. So a man who is sensitive to collarbones (especially if they’ve lived in communities where its always covered) may see my shirt as “suggestive” even if its not. Many people read into what they want to see or are used to.
KW example of high heeled shoes – my friend has strange arches and finds high heels way more comfortable than flats.
So while what KW writes is nice, its not all encompassing.
Minhag hamakom is not always easy to define – according to my Rabbi, Brooklyn (for example) has no minhag hamakom because of the diversity of the population.
So, in random conclusion, men should keep their eyes off women, women should stop judging other women and everyone should dress appropriately according to their shitta and weather.