What is Modesty and why is it so important for the Christian woman to understand, dress & behave modestly? Modesty is the voluntary personal responsibility to behave & dress in such a manner as to not purposely draw attention to oneself, to not think proudly of oneself and it's a decision to protect from purposeful or "unintended" enticement in inappropriate ways & places. This is crucial for a Christian woman; first and foremost because we're representatives of the LORD Jesus Christ and secondly, if we're married, we're a reflection of our husband.
It's critical to pay attention to the message and the signal our clothing is sending and to make sure, very sure, that the message our attire is giving is in line with the Word of God. If style & type of clothing is something you're wrestling over in your mind, or if you're feeling convicted about dress, and what in this world should a Christian woman be wearing, then pray, discuss these things with your husband or, if you're a young woman at home, your parents. Many will have ideas and convictions about what *you* should wear, but what matters most is what the LORD is directing and what your husband prefers.
Taken from http://www.achristianhome.org