Most fashion rules are not really rules. They are aesthetic beliefs, judgments that bring items to the runway. Some emerge and evaporate within a couple of weeks, while others hold much greater power. They can persist for quite a while, but trends ultimately dissipate. Take, for example, the slim silhouette that dominated the past decade. Today, it gives way to wider trousers and looser fits. Some men see this as an assault on style.

They believe that tapered pants are correct, suitable for the male body, enhancing it and flattering it in some way. A slim-fit jacket is seen as the platonic ideal for men. But in reality, it’s just a fashion image that held more sway than others. The things we reject for a long time are also the result of subjective opinions. These bastions of bad style – square or long-toed shoes, bootcut jeans, long hair at the nape of the neck – are not objectively bad. They are just unfashionable. However, time and designers can rehabilitate them.

In such a subjective world, only a handful of commandments are engraved in stone. These are the principles of knowledge about men’s clothing, the cornerstones of the skill of dressing. It’s not about trends or personal taste. They are dictated by clothing manufacturers. Clothing is designed by them to be worn in a certain way. Wearing it differently is considered incorrect. In this case, you won’t be unfashionable; you’ll simply be breaking the laws of fashion.

Rule 1: Never button up all the buttons on a jacket.

Certainly, if a garment has buttons, they should be fastened. However, the bottom button of any jacket is a deception, a vestige from the jacket’s distant ancestors. The jacket is designed to flare at the hips, narrowing the silhouette at the waist. If you button up all the buttons, unnecessary tension on the fabric and seams will be created, visually disrupting the silhouette. The same occurs if you sit down without unbuttoning the buttons. The suit should snugly fit the upper part of the body. When you sit, the back straightens, the fabric stretches, testing the craftsmanship of your tailor. An exception to this rule is a casual jacket, according to Christopher Modoo from Chester Barrie at Savile Row. The design of this jacket allows for buttoning up all the buttons, but it is considered outdated.

Rule 2: Cleanliness is not above godliness.

The notion that clothes should be washed after every wear is mistaken. This is only applicable to underwear. Other garments, unless you behave at the table like a pig, can withstand several days of wear. This is good for the environment and your wardrobe – the more you wash, the quicker your clothes wear out. This is especially true for suits. Dry cleaning is not a salvation, as the chemicals can damage the fabric and seams. Suits should be sent to dry cleaning no more than twice a year. Instead, brush your suit after each wear and let it air out for at least a day, advises Jeffrey Doltis from Savile Row Company. And try not to soil your suit unnecessarily.

Jeans also shouldn’t be washed frequently. Chris Bloxham, a denim specialist at Nudie Jeans, believes that jeans should be washed once every few months to keep them in good condition. Ideally, denim doesn’t need to be washed at all. The reason is that the dye on the fabric wears unevenly with wear, creating a distinctive pattern. Throw your jeans in the washing machine, and they’ll lose their individuality. Bloxham advises not to wash jeans for at least 6 months from the first wear. The more you wear jeans, the more unique they become. And never wash them in hot water or tumble dry them. This way, you’ll do less harm to the environment.

Rule 3: Don’t tuck in a shirt not meant for it.

It is generally assumed that shirts are meant to be tucked into trousers. However, this isn’t always the case; it depends on the style of the shirt, particularly its hem. Shirts designed to be worn with suits are cut to be tucked in. They are more formal and have an extended length at the back to ensure that when you sit, the shirt doesn’t pop out or bunch up above the trousers. If you tuck in a shirt meant to be worn untucked, you’ll have to monitor its position throughout the day. If you enjoy tucking in T-shirts, opt for longer styles and wear them, if possible, under a belt to avoid constantly readjusting the T-shirt.

Rule 4: Polish and shine.

Good shoes are an investment. However, you won’t be able to pass them down to your children if you don’t take care of them. In the military, sergeants are obsessed with shining shoes not just because they’re a bit obsessive (they are, of course, a bit obsessive, but that’s not the only reason), but because polished leather is better protected against wear. Tim Little, the owner of the shoe brand Grenson, believes that good shoe cream is like food for leather. It penetrates the pores and nourishes the leather. If you polish your shoes twice a week, it will make the leather soft and protected from moisture.

Rule 5: If you’re in a suit, carry a bag in your hand.

Backpacks are not just for hiking these days. Brands from Herschel to Louis Vuitton now produce backpacks. It doesn’t matter how luxurious your backpack is; it doesn’t go well with a suit. It’s not about combining formal and casual styles. It’s just that a backpack ruins your suit. Never sling a backpack over your suit shoulder. The pressure and friction can damage the fabric, leaving it greasy or worn. If a briefcase seems too formal, opt for a tote bag. Or simply carry your belongings in your hands.