NEW YORK (FORTUNE) - For people who make more money and drive bigger cars than anyone else in the world, American men are just a bit behind in the suit department.

Whether it's picking something great off the rack, or commissioning a beautiful bespoke suit, there's an art to looking your snazziest in and out of the office.

And according to downtown menswear designer of the moment Duncan Quinn, picking the perfect suit starts with a few basic rules that'll have any guy -- young, old, stylish or sartorially challenged -- looking picture-perfect with ease.

If you're paying thousands of dollars for a lovely suit, it should be the best. That means it's hand-stitched and fully canvassed, not "fused" (i.e. glued) or semi-canvassed. This is basic, and it makes a world of difference.

If you want to wear a suit every day, don't go for Super 200's -- i.e. a finer fabric -- because you'll wear it out in no time. For everyday wear, go for something under Super 100's, and the suit should hold up much better.

"None of this boxy rubbish," says the London-native Quinn.

Many American men wear their jackets one to two sizes too big. But if you don't want to look like a gorilla, you'd better get over the pinch and get a jacket with high armholes that fits your shoulders. Otherwise there's no way to get that "waisted" look.

The trend these days is to cut them like low-rise jeans, often with a boot cut. That favors a leaner body, and also allows the pants to fit over your shoes, for a clean look. (Quinn recommends a "guardsman" cut, so the hem is an inch higher in front and doesn't bunch legwarmer-style.) But if you've enjoyed the pleasures of fine wine and food, think about getting yours cut higher, for that elegant, elongated silhouette.

A guy with a size 16 neck can have a 30" waist or a 40" waist. Obviously, most commercially available shirts are cut to accommodate both, which means those on the smaller end can find themselves billowing out to parachute proportions. So take a little time to find a shirt that fits as closely as possible.

Wear them for the love of goodness, but no more than three at a time. It's fine to wear different shades of the same color, but be sure to contrast the color of your shirt and tie with your suit. (Or run the risk of channeling a monochromatic Sesame Street character.) Navy or midnight blue are good standby suit colors, and are great with pinks. If you opt for a black suit, keep your contrast color a bit more somber -- scarlet, gray or blue.

A good rule of thumb -- if you're feeling adventurous, but don't want to look like a fun house -- is to wear the same pattern throughout, but vary the scale. So a suit with large checks can be paired with a shirt that has much smaller checks for a safe bit of style.

If you're going with blue for your contrast color, you may want to consider making sure your socks, cufflinks and tie the same hue. And always, always, always cufflinks.

Check that they're sterling silver or gold, otherwise you're probably getting a lower-quality base metal coated in rhodium, which will last about as long as your first girlfriend.

You can buy off the rack and just worry about the shoulders and torso fitting correctly, because the right tailor can take care of the rest. And the best tailors can do miracles. "It's the difference between an aesthete and artisan," says Quinn, whose people can give you the star suit treatment at his eponymous New York Nolita store (www.duncanquinn.com), "between just measuring someone and doing something to fit those measurements, or really seeing him and envisioning something that will make him look his best."

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