Before applying kajal, always use an eye primer on your lids and under-eye area to prevent smearing. It will make your kajal last longer.
When applying kajal, try to use less kajal on the inner and outer corners, it will prevent the smudging of excess kajal.
Don't forget to use loose powder after applying kajal, it will prevent the oil or sweat on your skin and will help the kajal last long.
Try using a black or brown eyeshadow to define your waterline further. It will act as a setting coat to help it sit well in place.
People who have oily skin should always carry Q-tips with them so that they can easily wipe the excess kajal and restore a clean look.