Assuming you were inspired to ask this because of the photos I posted earlier tonight of my 80s look – I filled in my brows tonight with a brown Quo eyeshadow. I don’t normally do this, because my brows are plenty full/dark enough for me on most regular occasions – but since the theme was 80s, I figured I’d bring out my inner Jenna Rink and play ‘em up!
Overall, my best tip would be to see a professional and get your brows plucked, and thereafter just try to follow the shape that they created for you (assuming you like it).