Putting on a great suit is transformative. Your shoulders are broadened; your lines, longer and leaner; your waist, that much trimmer. You look great, you feel great. That is, assuming you got the right suit and had it properly tailored. As any man who's spent an evening in a boxy rental knows, there are very few things as good as a great suit. There are—in the sartorial sense at least—fewer things worse than a bad one. Since even a modestly priced off-the-rack number can look like a million bucks with the right nips and tucks, we're here to help with six essential rules for getting a perfectly tailored suit. 

1. Hem Your Trousers

This is the number one place most guys go wrong when it comes to tailored clothing. Even A-List stars—who should know better—have been known to leave things far too long. Though you don't necessarily need to embrace the ankle-baring aesthetic espoused by designers like Thom Browne, all that extra length isn't doing anything but making you look shorter and sloppier. Opt for a very small break (the edge of your pants should just brush the tops of your shoes) for a look that'll stand the test of time, but still feels modern. 

2. Make Sure the Shoulders Fit

The shoulders of your suit jacket should feel like they're hugging your own. If they're noticeably tight, the jacket is too small. And if the shoulder seams are sagging past the natural line of your body, like they do for all too many workaday types, it's too big. The shoulders are the one place that even expert tailors are hesitant to mess with: It's difficult, expensive, and can ruin your suit. Nearly everything else can be altered, but if the shoulders aren't spot on, it's time to return it to the rack. 

3. Hem Your Sleeves

Slightly less pervasive than the problem of pooling trousers—but no less pernicious—is that of over-long sleeves. Your jacket sleeve should end a quarter-inch to a half-inch before your shirt sleeve does. All the better to show a sliver of cuff. If your jacket sleeve is hitting your knuckles, it's way too long. This is an easy and cheap fix if the buttons on the cuffs aren't functional; your tailor will simply trim from the cuff up and then move them. If the cuffs feature working buttons, it's a bit more labor-intensive and pricey. The sleeve has to be taken up from the shoulder. Still, better than the knuckle-grazing alternative. 

4. Watch for Collar Gap 

You might not be able to see it, but everyone around you will. The collar of your suit jacket, if not properly fitted to your neck, will sit away from your shirt collar, leaving a gap. This can happen for any number of reasons, and if it's not too severe, a tailor can usually fix it. But anything more than a small gap can be a problem. Watch out when you're buying, and unless you've got a particularly skilled tailor that you trust completely, steer clear. 

5. Take in the Waist of Your Jacket

Many suit jackets are made with a "democratic" cut, which is a nice way of saying they're designed to accommodate men of a certain girth around the midsection. If you aren't one of these men, it also means that your jacket will look boxy until you have your tailor take it in at the waist. Don't get too aggressive about it, though. Remember, you still need to be able to move in the thing. Aim for being able to comfortably fit a closed fist between your jacket and shirt when the top button is closed.

6. Slim the Sleeves and Taper the Trousers

A lot of guys have tuned into the idea that going narrower on the pants is a great way to elongate the lines of a suit and create a tailored silhouette. Take a page from their book and taper your own trousers. One thing you might not have thought of is doing the same for the sleeves of the jacket. It's a little more complicated because your tailor will have to deal with the lining, but it'll make for a much more polished look in the long run. So, you know, worth it.