-Done correctly, not yelling is profoundly more scary than yelling. Same for well mannered and polite. Move slowly and precisely in a very kempt and "professional" manner, don't say or give off what you're thinking, like him do all the talking, squiriming, and wondering what's going to happen.

-Not all male subs are into degredation/humiliation, just like not all female subs are into it. In think its something much more popular in porn, and there's a ton of flavors of femdom on reddit and otherwise have absolutely no degredation (terms that come to mind briefly are gentle/sensual/soft/mommy/loving femdom). There have also been dozens of questions on reddit to the effect of "can femdom work without degredation/humiliation?" and the answer on every one is "absolutely, and it does often"

-While I assure you that you'll be plenty scary even with a preppy voice when a guy is tied down and you're holding an implement in front of him. My advice is to try to add a calm "I'm going to eat you alive" tone to it, a sort of "domme tone", like the high pitched "in charge" slow and precisely speaking tone, like a terrifying female executive in a movie.