"Your dress and grooming send messages about you to others and influence the way you and others act. When you are wll groomed and modestly dressed, you invite the companionship of the Spirit. Immodest clothing includes short shorts and skirts, tight clothing, shirts that do not cover the stomach adn other revealign attire. Young women should wear clothing that covers the shoulder and avoid clothing that is low-cut in the bront or the back or revealing in any other manner. Avoid extreme clothing, appearance, and hairstyle. Avoid sloppy or inappropriately casual in dress, grooming and manners." For The Strength of Youth, PP 15-16

President Kimball delivered a great talk many years ago at Brigham Young University entitled "A Style of Our Own." He encouraged us not to be among those who would follow worldly, immodest styles, but to have the courage to dress in a way which will send a message that our standards are different. Our dress will reflect the way we intend to live, founded on principles of the gospel of our Lord and Savior. It is impossible to expect a child who has been taught to love to dress in the immodest style trends of the day, to then change overnight to an entirely different wardrobe when they enter a Church university or a missionary training center, or when they are married in the temple, or even when they dress for the Sabbath day. Modest, proper styles must be taught almost from birth.
Elder L. Tom Perry (Gen Conf Oct 1988)

You young ladies have a profound influence on young, masculine behavior. Young men wear clothes they think you like. Their hair will be cut to please you. You can control how fast they drive their cars if you want. They will dress as grubby as you like. You need not dress in the extreme fashions of the world. Are you aware that fashions and styles are promoted because someone has a product to sell? The rightness or appropriateness or effect on a youthful society does not matter as long as it sells. But the day will come when the world will follow the ways of the Church. Its influence will be as though flowing from the stars to affect the actions of men. Your influence with young men is important. You encourage Church standards and dress and conduct.
Elder David B. Haight (Gen Conf Oct 1977)

And those of us who teach in church organizations--are we honest in living as we teach, or do we have a double standard? It was observed recently that a young married woman teacher appeared at church in a very short mini-dress. Can she be honestly teaching the dress standards of the Church while not keeping them herself? Shakespeare said it so well: "This above all: to thine own self be true, and it must follow, as the night the day, thou canst not then be false to any man." (Hamlet, act 1, sc. 3.)
Elder Delbert L. Stapley (Gen Conf Apr 1971)