Thicker, more defined eyebrows not only look youthful (some call it an instant eyelift), but they also frame the eyes beautifully. Eyebrow pencils, pens, and powders work wonders to fill in the gaps and shape the brows, while tints or mascaras deliver a natural look, and can even lighten or darken brow hair color. A way to know what you're working with is to use a clear brow gel to brush the hairs of your eyebrows upward. Doing this will help you determine your eyebrow shape and will serve as a guide for parts to fill and color. Then, use a brow pencil, pen, or powder (using a slanted brow brush) to fill in the gaps and add definition. To finish, brush eyebrow gel (choose a lighter or darker shade to match your current hair color) to seal everything in place.