For a subtle sculpt effect: Start at the beginning of the brow and draw a line at the bottom of your brow until the point where your brow starts to arch. Slightly blend in the bottom part of the line with a Blending Brush.
For the ultimate sculpt effect: Start at the beginning of the brow and draw a line at the bottom of your brow towards the end of your brow. Repeat at the upper line of your brow. Slightly blend in the bottom part of the line with a Blending Brush