Fit beats brand, price and everything else combined

I spent ten years on a shop floor watching men choose clothes. The single most reliable predictor of whether someone looked good wasn't what they spent. It was whether the thing fit, and most men were wearing something between one and two sizes too big.

Not because they were vain about it. Because they bought a size up once, twenty years ago, when they were briefly heavier, and never revisited it.

The five points

Forget everything else and check these.

1. The shoulder seam. It should sit on the outside corner of your shoulder, where the arm starts to turn down. Not on your bicep. This is the one measurement you genuinely can't alter afterwards — a tailor can take in a body, shorten a sleeve, adjust a waist. Moving a shoulder means rebuilding the garment. If the shoulder is wrong, put it back.

2. The sleeve. Shirt cuff should end where your wrist meets your hand — right on the bone. Jacket sleeve should stop about 1cm short of that, so a sliver of shirt shows. That sliver is the difference between a jacket that looks tailored and one that looks borrowed.

3. The collar. Two fingers flat between collar and neck, buttoned. Tighter and it strangles; looser and the whole shirt hangs off your neck instead of sitting on it.

4. The seat and thigh. Trousers should skim, not grip and not sag. If you can grab a fistful of fabric at the thigh, size down. If you can see the shape of your leg through it, size up.

5. The break. The fold at the front of your trouser leg where it meets the shoe. One small break — a single soft fold — is right for almost everything. No break for a sharper look. Two or more and you're wearing someone else's trousers.

Buy the shoulders, alter the rest

This is the whole strategy in one line.

Buy for the widest part of you — shoulders for jackets and shirts, seat for trousers — and then have everything else taken in. A high-street jacket that fits your shoulders and has been through a tailor will beat an expensive one straight off the rack, every time.

Alterations are cheap and men systematically avoid them. Taking in a shirt body: not much. Hemming trousers: less. Shortening a jacket sleeve: a bit more, still trivial against what the jacket cost.

What "too big" actually looks like

Men rarely see it in themselves. Symptoms:

• The shoulder seam is halfway down your arm.
• Your shirt billows at the waist when you tuck it.
• You can see the pocket outline through the trouser front because the waist is loose and being held by a belt.
• The jacket's bottom button sits well below your wrist when your arms hang.

The belt is the giveaway. A belt is meant to be a detail, not a structural component. If yours is doing real work, the waist is wrong.

Where to start

You don't need a wardrobe overhaul. Take the five things you wear most to a tailor in one trip and have them fitted.

The compliments will start within a week, and nobody will be able to say why.