There are a lot of different ways on how to apply eyeliner. Some like them thick, some thin, long, short, double, all over the eyelid or just on the end. You can choose between a pencil eyeliner or a liquid eyeliner. If you want a natural look with a smudged line you should use a pencil eyeliner. If your goal is to create a smooth and precise wing you should use the liquid eyeliner. Last but not least to achieve a cateye you can use a gel eyeliner.