I never really learned how to use makeup properly. In the 70's when I was in high school, girls who wore makeup were teased. So at a time when I would be learning about makeup and sharing tips with friends, I wore none.
My biggest tip for dark-eyebrowed girls is: try a greyer, ashier, taupier tones eyebrow powder / gel / pencil, because that is going to look more natural to fill your brows in. The ones in your exact hair color might seem overdrawn.
I've learned the art of blending makeup at a very young age. I used to see my aunt doing it all the time and that really got my attention. I think it's also a gift and maybe it's for the same reason that I easily learned to paint, self-taught, even if I'm already in my late 30's.