What is the best way to contour?

You know how enhancing your facial contours makes your face look fuller, smaller, and more attractive? However, even when I try to get some results with contouring makeup, it always looks strange or excessive on me, and I feel like it would be worse than not doing it at all.

I'm wondering if the product itself is the problem... how can I do it effectively? Would there be detailed contouring makeup tutorials on sites like YouTube?