In a matter of five seconds, she traces the outline of her lip like it's an abstract painting, but it inexplicably makes PERFECT SENSE. Here's how:
1. Begin lining at the outer corner of the left peak of the cupid's bow, drawing out towards the corner of your lip with short, painterly strokes.
2. Flip it and reverse it by drawing back to the peak of cupid's bow, then down to the valley of the cupid's bow, extending the line diagonally so that it's parallel with the opposite peak. The line should look like a boomerang. Repeat on the right side so that the two boomerangs criss-cross in the middle.
3. To line the bottom lip, compartmentalize: One section for the middle of the lip, then two others for the the mid-to-outer corners. 
4. To ensure color that stays put in the vulnerable inner corners, fill them in.
5. Finally, to center things, draw a straight line directly from the middle of your bottom lip to the top. Now, hell or humidity, you're ready for your primary layer of color.