1. use waterproof eyeliner. tears can cause eyeliners specially placed at the bottom lash line to smudge so make sure you are using waterproof ones.
2. use brush when applying an eyeliner. even when applying with a pencil liner, it is still best applied with a brush. all you need is a good liner brush like 266 angled brush or the 209 liner brush. brush it against the pencil and apply it the same way you would apply using the pencil directly. this allows you to evenly apply the product without excess which in time would end up smudging to your skin.
3. set the eyeliner with a powder eye shadow. make sure you use the same color shadow with the eyeliner that you are using.
4. lightly smudge edges of the eyeliner with a q-tip to let it fade off the skin. smudging it until it fades prevents having too thick edges which in time would smudge outwards. smudging the edges already will no longer make it smudge further.
5. apply face powder underneath the eyes right below the liner. this also gives a good blend to the eyeliner edge and make it appear like it fades off.