Applying a smooth, even line on the eye doesn't have to be a challenge. If you've ever tried to apply your eyeliner and ended up with a squiggly line instead of that dark, smoky one you imagined, you probably disagree. To get better results, rethink the approach.
Always keep the eye pencil well sharpened. As soon as it dulls, the quality (and thickness) of the line is affected. A nice, fine tip is easier to control and will cooperate. It's also more hygenic to sharpen between uses, since sharpening takes away all bacteria that may have gathered on the tip of the pencil. Don't take off too much; just a twist or two through the sharpener should do it.
For cream or liquid liner, always use the very tip of the brush and place it as close to the lash line as possible. This helps create a thin, controlled line. To thicken, add additional lines from there, but remember that it's harder to make that black line skinnier if need be. For a cream liner, try wetting the brush before picking up the liner. This turns the cream into a firm, liquid liner that will last all day. The same technique can be used to turn eye shadow into a liner.
To get the best line possible, stop stretching your eyelid out to the side and drawing straight across your lid. Doing that can actually loosen the collagen in your sensitive eye area, which leads to crow's feet in five to ten years. Not to mention, once you let go, that once perfectly straight line looks a lot wavier.
Instead of using the old stretch-and-trace routine, try a new approach. Using one hand, lift your eyebrow straight up, turning your eyelid into a nice flat canvas (up and down, instead of side to side). With your other hand, place the tip of the pencil right into your last line and draw smaller lines between each of your lashes, all the way across. This connect-the-dots technique will give you a nice, thin, straight line across the lid. And when you let go and the eyelid drops, it will still be straight. Doing it this way, you can better control the thickness of the line.
It might take some practice to get used to moving the hands in this new way, but it certainly gives better results! Save yourself from have to re-draw the line again and again (and save the make-up remover!) with this new technique.