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I would say a properly focus calibrated lens helps tremendously. Single point autofocus on the eyes is really all there is to it, but a calibrated lens will make the focus dead on. F-stop just depends on what depth of field you're wanting. as long as it's focused on the eyes, you'll be golden, but people usually prefer the rest of the face (IE nose) being in focus too. I like the look of a 70-200 at 100mm or so at f/4, but it also depends how far away from the subject you are.
really, the stunning photos I see on this board are due to an incredible eye for composition, proper lighting, and a beautiful subject
For these photographers, the settings are of secondary concern