Prepare your eyebrows for filling
First of all, pick a small toothbrush or makeup brush and comb out your eyebrows from one end to the other. It helps in identifying the areas of the eyebrows that require filling.
Fill in with eye-pencil
Filling eyebrows with an eye-pencil is the simplest way to enhance your sparse eyebrows. Select a good quality eye-pencil that is a shade lighter than your eyebrows, and hold it in a horizontal position to your eyebrow. Now, gently apply it in the direction of your eyebrow hair growth until you get the desired look.
Note: Always avoid hard eye-pencils as they are usually too waxy, resulting in an unnatural look.
Apply Eye shadow or Brow Powder
Eye shadow or brow powder is another simple idea to fill your eyebrows. Choose an eye-shadow or a brow powder which matches the natural color of your eyebrows. Take a specially designed angled eye brush and dip it in the selected powder. Now, gently apply it along your eyebrows, filling them thoroughly.
Note: You can replace the angled eye-shadow brush with a clean mascara wand. Secondly, slightly dampen the eye-shadow brush or a clean mascara wand before plummeting it into powder. It holds the powder for longer period of time.
Use a clean mascara brush
Take a spare mascara brush and wash it with water to remove the mascara. However, you can buy a clean mascara brush from your nearest beauty store as well. Hold the mascara brush full grip move the loose eyebrow hair into the sparse areas for more natural and balance look.
Note that filling in your eyebrows is a temporary solution. If you're looking for a long term solution to make your lighter eyebrows look darker and thicker, you should either know how to color eyebrows or else growing eyebrows thicker naturally.