My first rule is that a man should always wear a suit to a job interview. I don’t care if you’re trying to be a janitor or a CEO; wear a suit unless you're told otherwise. Second, make sure your suit fits. You might as well wear your PJ's if it doesn’t.
But just getting a suit on your body doesn’t mean you’re done. Men don’t have much flexibility when it comes to interview attire, so attention to details can be the best way to set yourself apart from other candidates. Try to stay away from plain black. The fact that you’re wearing a suit is formal enough, and unless you’re applying for a job on Wall Street, you don’t have to be quite that conservative. Grays, navys and subtle patterns will look just as professional, but will also give you an opportunity to differentiate yourself.
Ultimately, the most important thing is that your suit fits you. You'll probably want to go with a slim-fit if you opt for a less expensive suit. But whether you spend $100 or $1,100, get it tailored. A sloppy suit sends your interviewer the same message as a pair of sweatpants: namely, that you don't care.
up next: the shirt
*I used Park and Bond as a template to easily display these suits, and also because they have great clothes, but it is obviously not the only place to find the best suit(s) for you.