I don't like piercings in general, but for you I'd make an exception. :) And I'm not flirting, I mean just for this question. :)
Eyebrow piercings remind me of thugs, those kind that wear tonnes of leather, act tough and 'bad' and think they are cool. I don't know why they have that effect, but I guess it because of all those 'punk rocker' stereotypes. Or something.
Rings on your eyebrows look a little weird. They hang down and make it look like you want to attach chains and other such stuff to your face, as well as possibly intending on hanging it up when you get indoors, lol.
Studs are nice, though. They can really contrast well with your eyebrow colour and skintone if correctly picked - I've always found silver studs to work well with black men, for example. They'll normally be double studs too, one at the top and one at the bottom of of your eyebrow, so they'll add even more imposing features to you, too.
I guess it also depends on how you wear your hair, from having no hair to having long hair - and if you have long hair, it would get stuck on them! So be careful, lol. My hair gets stuck in my glasses all the time, especially when it's windy. And that's embarassing.
Wearing hats with them also look good, I have a friend who has a silver piercing on his left eyebrow, and he wears a sort of miniature fedora when he is outside. You don't see the piercing until he is directly talking to you, and it always catches his attention and adds an imposing nature to his stance.
So long as you go through all the piercings and compare them to your dress style, hairstyle, complexion and such, it should be alright. Add a memorable, interesting touch to you, as well. :)
Overall I dislike piercings as I said, but it doesn't mean they aren't effective. :)