If you want a proper fitting jacket or suit, the kind of snug but comfortable fit found on custom pieces, then you have to learn to speak your tailor's language. Ask anyone in the business—new school guys like Kirk Miller of Miller's Oath to the legendary Martin Greenfield—and they all agree. You don't need to master tailor terminology, but you should communicate honestly about how you want your suit or jacket to fit. No detail is too small. After all, their whole business is about small changes that have a big impact. Here's what to ask for the next time the tape measure comes out.