Regarding looking "sexy," all I can ask is: why? What is the purpose of "looking sexy"? This one baffles me. I'll no doubt be dismissed out of hand by many as a "puritan" or "legalist" or something akin to this, but I really don't understand what benefit there is in "looking sexy". Leastwise, if you compare the benefits of modesty, and the perceived benefits of "looking sexy," I don't think there's any way modesty could lose out.
I'm with you on this one. No modest woman should be trying to look "sexy". Being neat, clean, and tasteful are one thing; purposely trying to attract/excite sexual feelings in men is not simply inappropriate, it's sinful.
A big problem we have here (and I fail on this score as badly as anyone else), is that we live in a culture that is in many ways at odds with Orthodox Christianity, particularly in the "practical sphere." Though we're supposedly in a pluralistic culture, it takes some courage to be "different". Whether it be refusing to swear or enter into smutty conversation with co-workers and peers (and not looking too pleased when others insist on doing such around you), stopping to pray first before eating in public, or any of the other little things we all do as part of our daily life...to do this requires a little bit of courage.
It also takes some courage on the part of women (particularly young women) to not copy the unchaste fashions of their peers. However, these things are all, directly and indirectly, ways of testifying to Christ before others - and if we fail to do this, He will not testify on our behalf before His Father.
While it is the Church's nature to have Her arms open to the world (Orthodoxy is not supposed to be a tribal religion, as the religion of the Old Testament tended to be), I think it may be time for Christians to take seriously that they're not "just like everyone else". That is to say, perhaps things are so bad in contemporary society, that we really should start "sticking out" just a little bit (rather than modify our habits to mimick the world.) We are a "peculiar people", and if what the world is doing around us is simply not moral, we shouldn't copy it out of human respect.
While I don't think we need go as far as say, religious Jews or Muslims do in their manner of dress, to some extent I think they have the right idea. Our difference being that we're neither "luddites" (simply canonizing certain styles of clothing for no reason other than fear of change), nor do we have it in our heads that we must dress in every detail like Christ (as the Muslims do with Muhammed.)
Seraphim