Learning how a shirt should fit you can take surprisingly long – as most fans of bespoke try far fewer shirtmakers than they do tailors. Once learned, however, the lessons are fairly simple. They are becoming particularly clear to me as I complete my shift from Turnbull & Asser to Satriano Cinque. (Updates coming soon on the latest shirt commissions from them.)

1. It’s not about the waist

The biggest lesson is not to obsess about how a shirt fits on the waist. To a young man trying to look as sleek and athletic as possible, a closely fitted shirt is an understandable focus. Italians heavily dart their shirts to this purpose; in the past I have darted and redarted my own darts in pursuit of that same, perfect fit.

There are two reasons why this is a mistake. The first is that cotton has no natural stretch, unlike wool, so you cannot fit it as closely to the body. And of course you can’t undo a shirt when you sit down. Always try sitting and slumping in a seat when trying on a shirt: if there is any discomfort, the fit will be intolerable after a day sitting in front of a computer.

The second reason is that the fit on the waist is affected by other things. Most particularly length. Men often make the mistake of having their shirts too short, so they pull out of their trousers too easily and bunch unattractively above the waistband. This is also caused by a shirt that is too tight on the hips. If there is no spare room there, the shirt will be forced upwards, creating more bunching.

2. Focus on the collar

The most important thing to focus on is the collar. Here, millimetres make a difference. While the height of the collar should always be in proportion to your neck, most commercial shirts are too low to give the tie any space to arch outwards. Particularly English shirts.

The tie arch can be aided by having a larger tie gap, between the two sides of the collar. And of course the shape of the collar itself is subject to many permutations. Find something consistent and probably conservative, and stick with it. 

Ideally, the shape should work with and without a tie (so not collapsing underneath the jacket’s collar). If that’s not possible with your jackets and neck shape, have just two collar types: one for a tie (perhaps a medium spread) and the other for an open neck (probably a buttondown).

3. Consistent sleeves

Sleeve length is important, but the key thing is consistency. Shirt sleeves can be shortened quite easily, and more cheaply than a jacket. But only double cuffs can be lengthened, and not by very much. A quarter to an eighth of an inch is enough when your hands are at your sides; remember far more will be on display when you extend your arm.

In the end, shirts are pretty simple. If you can find a great ready-to-wear collar, all you need is for the body and sleeves to be long enough. Then buy a lot of them.