WORN WITH A UNSTRUCTURED jacket and a mullet, it makes you look like a veteran coke dealer. Wear it untucked over denims, with sea-grass flip-flops, and you come across very Calvin Klein. Team it with a grey suit and striped tie and you are transformed into the father of all salarymen. You get the idea. Every man, whatever his age and station, needs a white shirt. Albert Einstein wore nothing but white shirts, as did Mickey Rourke in 9 1/2 Weeks. The scene where he opens a wardrobe to reveal half a dozen white Comme des Garcons shirts is more arousing than any fridge-fuelled romp with Kim Basinger. Maybe. The theory of white shirts is so scholastic a roomful of philosophers could debate it for days. But you are time-poor. This column has therefore distilled its essential teachings. 1. Have it tailor-made, especially if it's for business. You can have a $300 shirt run up in no time. According to Roshan Melwani at Sam's Tailor, Nathan Road, Tsim Sha Tsui: 'It's too important to leave to chance. This garment is an essential part of every man's wardrobe. It's clean, crisp and goes with everything. It's fine for every occasion. So do the right thing and get it properly made.' But he would say that. 2. Get French cuffs. Button cuffs are for geeks and schoolboys. Players wear cuff-links. 3. Ensure the sleeves are long enough. Style factions argue whether the shirt sleeve should be half a centimetre (conservative) or a centimetre (flashy) longer than the jacket sleeve. But it must be longer or you'll look naff. 4. Avoid monograms. Nobody wants to read your initials in gothic capitals, thank you. 5. Button-down collars are uncool. Says Roshan: 'Button-downs have never taken off outside the United States: they look too 'bachelor'. In now are large, spread Italian collars.' 6. Wear them untucked occasionally. Take your cue from Tom Ford (below) and stop forcing your shirt tails down the back of your pants. Relax, man. 7. Replace them frequently. White means brilliant white. It doesn't mean that greyish white that comes from one too many washes. 8. Do not button to the top unless you're wearing a tie. Otherwise you'll look like a superannuated member of the Human League. 'Of course it also depends on the shirt,' says stylist Emma de Teliga. 'Never button a classic white business shirt. But with a slightly heavy or linen shirt it could be okay.' 9. Soft collars are for casual wear. So are raw-cotton finishes and hemp textiles. A suit always looks best with a stiff-collared, fine cotton number. 10. Don't try to pass it off under a dinner jacket. Come back when you're wearing a proper dress shirt, sir. Follow these rules and you won't go wrong. While smart white shirts are wardrobe staples, they are not created equal. And you don't need to be Einstein to understand that.