Sometimes it's hard to have a steady hand while you do your eyeliner. It can end up looking uneven, messy and too thick. This is a quick fix I use to touch up my liner when I'm short on time but still want it to look good.
1. Apply your eyeliner as you normally would.
2. This is how my liner tends to look when I do it quickly, without touching it up. Uneven and messy.
3. Using a short angle brush, retrace over your liner with black eyeshadow. The black eyeshadow will smooth out the edges, fill in any light spots and soften everything. Wa-la!