…about waterline eyeliner:
Use a thin stick to apply it. Using a thick stick really increases the fallout from the powder and you will be spending the best part of a half an hour cleaning up underneath your eyes before venturing out.
Trust me on this.
[...]

A Second Great Truth I Have Learned…
…about waterline eyeliner:
If you do get some fallout below your eye, try smudging it and incorporating it into the whole eye’s makeup. I did that today and it made for a great looking smokey eye with much less fuss overall. It really worked when I put regular waterproof eyeliner on the upper lid. [...]