"You choose your lens and light according to what you want to say," he told me. "If you want to say funny or grotesque or comedic, you might use a more wide-angle lens. But for beauty, you want to use as long a lens as you can. You want to flatten, to make the nose as little as you can. The wider the angle of the lens, the bigger the nose. So we use long lenses."
That little paragraph contains a whole lot of wisdom that's especially useful for portrait photographers. So I decided to break it down a little more.
Start by determining what you want to say with a portrait. Too many of us inadvertently skip this part, but it's really the starting point for any good photograph. Ask yourself, "What do I want to say with this picture?" In the case of a portrait, it's really a question of what story you're trying to tell about the subject. Are they a goofy comedian, or a serious attorney? Do they want to look especially serious or comedic for some particular reason? Or do you simply want to make them look as attractive as possible? Believe it or not, starting here makes the rest of the process—determining light and lens—that much easier.
That first decision paves the way to inform your lighting choices. While it's possible to achieve flattering beauty lighting with a variety of light sources (and equally possible to make someone look grotesque—accidentally or not—with those same lights) the easiest and most foolproof way to make a beautiful portrait is to choose a broad, soft source. Indirect window light, for instance, or a large studio softbox positioned frontally for minimal shadows and texture gives you a great shot at flattering their face and pleasing your subject.
Finally, you're ready to think about the lens choice. More than anything, it's the lens that will dictate whether your subject looks dainty and beautiful or distorted and grotesque. Quite simply, using a telephoto lens (let's say 80mm, 100mm or even longer) will compress the scene, keep the subject's nose nice and petite, and generally prevent them from appearing distorted and round. This last thing—a distorted and round face—is the very thing that wide-angle lenses positioned close to subjects do really, really well. If you follow Schatz's advice of choosing the longest lens your reasonably able to wield, you'll unfailingly compress the scene and keep the subject's facial features from being distorted. Combined with the right light to tell the story that you've planned from the start and you're well on your way to portrait success.