I want to know how to contour well.

I want to create a three-dimensional makeup look using contouring.

This desire to add shading to a plain face to make it look smaller and to raise a low nose.

I've watched YouTube videos but I still don't understand. If you know of an easy and simple way to do contouring well, please share it.

I don't know exactly, but it seems like I need to grasp the underlying principles to properly adjust the shading to suit my face.

It would be so, so great if there were some kind of formula.