A new suit is a wonderful thing. If it fits right, if it’s well made, then slipping into tailoring is like shrugging on confidence. You feel more attractive, more secure in your decisions. And other people can see the change. Unless, of course, you forget to deal with these little details. Don’t look like a n00b.

You Don’t Cut The Vent Threads

A vent is a slit up the back of your jacket. Like all manner of menswear details, they’re leftover from the suit’s time as uniform – it let the jacket sit over a saddle without bunching. Italianate tailoring tends to be single-vented, whereas British suits prefer a slit up each side.

Whichever style you pick, at first wear they’ll be tacked shut by a small ‘X’ of thread, which stops the fabric getting rumpled up when it’s being shipped or hung in store. Slit these before you wear it or that X will make the spot where your panache died. Your new jacket also won’t sit properly, since the material will pull around your seat. Which is doubly embarrassing.

You Do Cut The Pocket Threads

As you’ll discover when you first try to stow your keys in your jacket pocket, the factory sewed them shut. Again, that’s to make it look better on the rail; the fabric sits flat and the men who try it on can’t stuff their fists in the pockets and stretch the jacket out of shape.

Leave them shut. Because otherwise you’ll be tempted to stuff your fists in there and stretch your new jacket out of shape. You shouldn’t ever put anything in your outside pockets anyway – it makes the fabric bulge and hang lopsided – and the thread will allay that temptation. Although if you’re a pocket square guy, feel free to open up your breast pocket to make space for a silk. But never a phone.

You Leave Your Functioning Cuff Buttons Undone

If you are wearing an expensive suit with surgeon’s cuffs – that’s functioning buttons on the sleeve – your tailor might advise you leave the last one undone. Working buttons have long been a feature reserved for spendy tailoring, since they take more work and skill than just attaching a button to solid fabric. By leaving the bottom one open, you let everyone know just how much your suit cost.

There’s two problems with this. First, you shouldn’t be the kind of man who needs everyone to know how much his suit cost. It should be obvious from the fabric and fit, anyway – undone buttons are just needy. Two, because so many men equate working buttonholes to quality, brands now include them even on cheap suits; for an extra £5 production cost they can charge a three-figure markup. And while you’re fiddling with your cuffs, everyone else notices your suit’s cheap fabric and glued-in canvas.

You Don’t Remove The Shoulder Stitches

That line of cotton down your new suit’s shoulder is not a design flourish, it’s a hangover from the days when all suits were bespoke. A tailor would make adjustments to its fit on your body with temporary ‘baste’ stitches, which would be removed when the suit was permanently altered.

To hark back to that Savile Row tradition, some brands leave these stitches in place. Or, more accurately, sew them on before bagging their suits up. They serve no purpose other than to make you look like you don’t know why they’re there. If you rip them out you can tear the surrounding fabric; instead, snip in the centre and gently tug either end.

You Store Your Suit On Cheap Hangers

You’re an adult, so you’ve hopefully graduated from the floor-drobe. But the wrong hangars are just as damaging. A suit is designed to hang from your shoulders, to follow its curves then drape over your chest and back. And unless you’re a Saint Laurent model, you’re probably a touch wider than a wire coat hanger.

Stow your jacket on something that thin and the metal puts huge amounts of pressure through the shoulder, stretching the fabric and reshaping its padding. Good if you’ve got hanger-thin shoulders, less so if you want your suit jacket to actually fit. Instead, get wide, wooden hangers that finish just before the shoulder seam – too long and they’ll stretch the fabric, too short and the arm will droop, changing the jacket’s shape.

You Iron It After You First Wear It

A day in the car, or slung over a chair back, wrinkles up your nicely pressed suit. So it’s understandable that you heat up the iron to press those creases back in. Bad move. Applying heat directly to suit fabric flattens its fibres and they grow shiny. Your sober business suit suddenly looks like you got it out of a football pundit’s wardrobe.

Protect your tailoring by letting gravity do the work. Suit fabric is resilient; hang up your jacket (on those nice, wide-shouldered hangers, of course) and over 24 hours most creases should simply drop out. For anything more stubborn, pass a handheld steamer over the arms and legs. Avoid steaming the chest – on cheaper suits it can melt the glue that holds the canvas in place, which harms the structure and can cause bubbling in the fabric.