1. Set a good example.
2. Look at anyone who appears in public inappropriately (e.g. too short a skirt, too low a neckline, too expensive a suit, too flashy a necktie, too expensive a car) as being weird.
3. Consider how a law firm looks at someone who shows up for work in sneakers, shorts and a flashy “vacation” shirt — or how a geek-oriented hi-tech firm deals with someone who insists on wearing a suit and tie. Most of the human race has strict and intricate dress codes – without have to write them down.