You can dress very stylishly, and nicely, as a Christian woman without showing everything. Christian women should not show a bunch of cleavage, I think that is first and foremost. Not a lot of skin. Not skin tight dresses or jeans that look like you had to be poured into them. Modesty is a virtue; that doesn't mean you have to cover up from head to toe, it means, exercise some common sense. You can look attractive without looking like a tart, and I don't think there is a woman living who doesn't know the difference.
By the same token, this does not mean that Christian women should be drab, colorless, or tasteless dressers. A Christian is to be a light to the world (Matthew 5:14-16), an example of balance and good taste. We should not be so out of step with the fashions of society that we stand out like the proverbial "sore thumb." Clothes can be fashionable without being immodest or peculiar. Apparel should be appropriate for the occasion—decent swimsuits for the beach, jeans for yard work, and usually a dress or other nicer outfit for special occasions. A Christian woman should especially strive to look nice for her husband and family.
In the Old Testament, God gives this law: "A woman shall not wear anything that pertains to a man, nor shall a man put on a woman's garment, for all who do so are an abomination to the LORD your God" (Deuteronomy 22:5). This refers to transvestism or cross-dressing, not to a woman's wearing of pants that are designed for women. The simple principle is that men should look and dress like men—masculine—and women should look and dress like women—feminine. By doing so, we will both glorify God.
The "meek and quiet spirit" of a truly converted Christian woman will be reflected in the kind of clothing she selects (I Peter 3:1-4). She will wear what is appropriate and stylish for any given occasion, but with proper modesty and decorum. And God will look on the heart of such a woman with approval.