The worst thing one can do is overpluck. (Well, not the worst...but it's definitely up there on the list.) Be careful because once plucked, your eyebrows can take months to eventually grow back. Until that happens, fill in bare spots with a brow powder or pencil. Use light, feathery strokes to create a realistic look, rather then drawing a line. Set the color with brow gel.
1. Find a pencil color that matches your brows as closely as possible. Brands like Revlon & Rimmel have a wide variety of shades, so it's easy to find the right color for you.
2. Don't have a pencil on hand? Try an eyeshadow that matches your brows, you can fill in color with shadow, although it may not look as realistic. Be sure to use a fully matte eyeshadow. No one wants glitter caked in their brows.
3. Pick up a good brow gel. I haven't seen any at Wal-Mart. Make Up For Ever, Benefit, and Anastasia all make great ones that can be picked up at Sephora. Worst case scenario, try a clear mascara.
4. Keep brows in place with a spritz of hairspray applied to finger or a toothbrush. Brush brows in place.
5. Next time, get brows professionally tweezed, waxed or threaded. Follow the "map" created by the professional with a pair of tweezers in between salon visits. This will help keep you from overplucking again.