1. Make sure that you pencil is sharp. Dull liner takes dull effect. You don't want a dagger, either, so twist it in a sharpener two times.
2. If you line your whole mouth they will look unnatural. Focus on the top lip. It's usually the one that needs definition: Using feathery strokes, work from the middle out to one edge, then to the other. Line only the center of your bottom lip and don't apply on the corner.
3. Always blend downward. Blending upward makes liner more likely to bleed.
4. If you are not sure with the color try a pinky-nude. It works for most skin tones.